I think the Belgians keep clear of the Ardennes, remain neutral and armed in the north, and fall back on British diplomatic support. The British very well may extend their neutrality into the fall in this case.
A Belgium declaration of war against an invader would be mandatory if it was serious about maintaining its neutrality.
The Belgian Treaty was signed in 1839 during the period of Splendid Isolation while the Entente Cordiales came in 1904 and 1907. The Ententes were with two of the guarantors of Belgium and aimed at the other two guarantors of Belgium. This is our first hint that the 1839 Treaty and the Entente policy were mutually exclusive. So, when you say, "stick with Belgium and France", what that means practically is Belgium with the Entente, against Germany.
You are ignoring the fact Belgium as an independent sovereign nation. You are ignoring the fact Belgium neutrality was recognized and protected by international treaty. You are ignoring the fact Belgium was not aligned with Britain, let alone a puppet of Britain. You are ignoring the fact there was no obligation compelling the British to come to the French rescue in the event of a German attack - let alone a German cold shoulder.
Germany has three strikes against it. First, Britain is the leading European power and dominant at sea with Belgium having a colonial empire and needing sea trade, (the fact that Belgium even had an empire in the Congo is indicative of some long ago British calculation on how best to control Belgium).
What would be the legal basis of a British blockade of a neutral Belgium? OTL, Britain did not declare a formal blockade of Germany, but instead relied on a doctrine of retaliation. OTL you are claiming Belgium would be intimidated by the Royal Navy, when OTL the better part of the Imperial German army failed to do the same.
So, between Germany and Britain, big advantage to Britain. The second strike was that the Kaiser was seen as untrustworthy and unstable, where as the British king and government were a bedrock of political stability.
Belgium was not a party to the British hysteria arising from the Anglo-German naval rivalry. Belgium had amicable relations with Germany, despite the expectation Belgium would become a thoroughfare in the event of a war between Germany and France. In this scenario, Germany passing on the opportunity to invade Belgium likely gives the relationship a further boost.
The third strike was that Germany was on the cusp of hegemony in Europe, where Belgium could fully expect to be swallowed into its orbit, if not annexed outright, after a German victory. Net these three together and you have a strong Belgian predisposition towards Britain.
Western Europe had endured over forty years of peace following the German/Prussian defensive victory of 1871. The rise of Germany, coupled with British isolationism had coincided with unprecedented peace and prosperity in western Europe. How do you get to Belgium being annexed by Germany?
In terms of the violation of the Ardennes by France, the British could, (and would) adapt the position that the French had acted unilaterally. A German violation was easier diplomatically for Britain's interests, but a French violation had the potential of a better military outcome. No violation at all would be a catastrophe, as the Franco-Russian alliance would not survive.
The British did not share a hive mind. The majority of Britons did not share Grey's fascination with the French, nor Crowe's hatred of the Germans. The British hawks are going to struggle to get Britain into the war without a German violation of Belgium's neutrality. Not impossible, but its going to be increasingly more difficult to justify British involvement if the Germans remain on the defensive in the west. Unilateral French action in the Ardennes will sink the Belgium and Britain public opinion of the French and cause the hawks in Britain to lose whatever credibility they were clinging to.
The preservation of the Franco-Russian alliance is not something Belgium or Britain would lose any sleep over.
If Germany deploys 6 armies in the West and 2 in the East and awaits the French, and Belgium north of the Meuse is inviolated, the net effect as of December is stalemate on all fronts. The Western Front will see the French defeated along the common border and soon losing steam. The front will run through Metz-Thionville up into the Ardennes to the Meuse. On the Eastern Front the Austrians have done better. But this war too is what the war was - a stalemate settling into a long conflict. Belgium's reality will be that their territory is in the front line and the war is not ending anytime soon.
Whatever the initial deployment, there will likely be at least 4 German armies in the east before winter. The position of the Russians will be either dire or catastrophic depending on their reaction to the initial defeats - immediately abandoning equipment and territory being their best, but least likely choice. Any pause in the east would be attributable to either logistics or the weather - not the ability of the Russians to resist.
In the west, heavy French offensive losses mean Joffre will eventually have to resort to OTL partial offensives, which means the French losses will continue to be disproportionately higher than the German defenders. Even if the French attempt an offensive into the Ardennes in 1914, it will not be enough to put the Germans under any serious pressure. The Russians would be in far worse shape than OTL and the French would (appear to) be doing nothing.
Meanwhile, Belgium is sitting pretty. The expected German invasion never came and the Germans are now defending Belgium honor in the Ardennes - although close observers might note the Germans appear to be luring the French further into the Ardennes rather than expelling them. The Belgium military will be sitting safely behind a chain of modern fortresses, defending the Belgium heartland from the fracas, which was the purpose of their construction.
Which of Doughty or Joffre commanded the French army in 1914?
Was it the same one who thought destroying his private papers (including any record of an Ardennes offensive plan) was the best way to preserve his legacy?
550,000 French troops were ordered mobilized north of Metz-Thionville on 2 August for a picnic? The French advance commencing around the 23rd into the Belgian Ardennes was totally unplanned? This is what you believe?
As previously stated and ignored by you, the above deployment was defensive and planned in response to an expected German invasion of Belgium. As previously stated and ignored by you, a deployment to defend against a German invasion of Belgium is very different from a French invasion of the Ardennes with an expectation of reaching the other side. The defensive nature of the French deployment is reinforced by the missive sent to Joffre by the Messimy (French Minister of War) in Aug-1914, reminding Joffre (in writing) he was not permitted to cross the Belgium border before the Germans. In the event, confirmation the Germans had crossed into Belgium reached Joffre before the missive.
Wilson is irrelevant for reasons already explained. Grey didn't want Britain to have any part of French planning. The RN would guard the coast and the Cabinet would look after the BEF as the war was breaking out. The British literally had no interest in discussing the Ardennes with the French. Whatever France would decide or do, because Germany was the threat the British would back them, but only after the fact. Not before it. I don't know where the confusion is coming from, because the terrain is clear. Belgium was subordinate to the Ententes, but that doesn't mean Britain was going to be the one to force the act.
Wilson was reflecting the opinion of the British population and cabinet, which you appear to claim is irrelevant. There was extensive military co-operation/ liaisons between the British and French before the war on a variety of matters. The Belgium territory was not discussed because the violation of Belgium neutrality was repugnant to both the British and French politicians. In 1914 Britain was bound by treaty to protect Belgium's neutrality, but it owed France sweet nothing.
If Germany invaded the Ardennes the British would go to war with Germany. If France invaded the Ardennes the British would go to war with Germany. What's the confusion on that concept? You believe British politicians a bunch of angles, incapable of wearing the daddy pants when it came to hard realpolitik choices?
The true masters of diplomacy in the decades leading into WW1 were not the British, but the French. From being a diplomatic pariah in 1871, France gathered Russia and then Britain under its wings and convinced them France's causes were their own. French diplomacy recognized the British were not ready to contemplate the violation of Belgium neutrality, as did Wilson. Ultimately the French and British ended up fighting for Russia's cause in the Balkans.