1940 British/German peace WIs seem to be really popular right now for some reason, but I've never understood why people would assume that the British would just happily sit out while the last remaining great european continental power gets butchered by Germany (and Japan in some instances), and why the US would get even more neutral than prewar.
A peace in 1940 is merely a pause until Germany invades the USSR, as even British politicians willing to make peace would understand that Germany would remain a huge threat to their interests, even more so if they take control of western USSR. What this POD would do is effectively allow the British to recoup their losses, actually put proper weapons into service instead of rushing older equipment to replace losses at Dunkirk (not all that likely though) and get the Commonwealth forces to North Africa or mainland UK, as I highly doubt that the British would accept a peace deal where they can't ensure their security.
By the way, what about the war with the Italians? Same treaty as with Germany?
Similarly, the fact that there's peace in Europe for the time being doesn't mean that the US won't implement their post-Fall of France military reforms and pre-mobilization plans, or send equipment that the UK sometimes bought itself, sometimes even according to prewar agreements. And the moment the UK goes to war again, the US will likely support them or even intervene.
So honestly I don't think that a 1940 peace POD would change how the war develops after Barbarossa, unless the Anglos prefer the taste of the Anglo-American/Nazi war.
The problem is that I posed my question in order to get an impression of how a German-Soviet war would have progressed without British belligerency. If I wanted to know how a German-Soviet war would have progressed with British involvement, I would have opened a history book.