Germany and Britain both offered naval agreements from time to time from the turn of the century until the outbreak of war, and they were all undermined by Germany. Anglo-German relations were actually on the mend when war broke out, as there hadn't been a serious issue for a while. Anglo-German tension wasn't solely caused by the Naval race, although that was a major contributor. Germany's quest for a "place in the sun" coupled with a consistent lack of understanding of British goals, objectives, desires, interests and policies meant that Germany tread on British toes time and time again. The fundamental issue, as I see it, was that the German foreign ministry and leadership believed that Britain needed an alliance with Germany as a fundamental element of policy, whereas British policy was that they needed to end their isolation and reach out towards a continental alliance, but that who is was was not vitally important so much as ensuring the balance of power remained intact. This was, of course, a multi-decade process, so depending how far back your naval assurances are the timeline could be substantially changed. By the 1911 crisis, Britain had picked a side between France and Germany, and it was just a matter of degrees - a naval agreement after this is not going to change anything, and an alignment before that would mean British support for, or at least not British opposition to, Germany's claims. Three-plus years of difference is going to put the whole situation out, and would almost certainly butterfly the Archduke's assassination. Germany and Britain cannot return to their previous diplomatic state due to substantial changes in diplomatic goals from both parties. Britain abandoned isolation as being no longer in its interest.
If one argues in favour and one against, there isn't really a consensus. IIRC there were some who stated they would resign if Britain went to war prior to Belgium's territorial violation, but they were not a majority of the cabinet, and the Prime Minister's vote would have been decisive.
I cannot see Russia starting anything with the same actors in place. Nicholas was enormously worried about war with Germany, particularly if coupled with Austria. Wilhelm had a tendency to agree with whomever he spoke to, and the German military establishment was quite aggressive and the Austrian extremely so, which points towards one of those two starting the ball rolling. If you want different actors, you'd probably need to look at a PoD prior to the Anglo-French alignment, but sufficient butterflies to cause a different mindset in Russia could also affect leadership in France, Italy, Germany, Austria and Britain. Historically, Russia felt capable of taking a strong stand in favour of Serbia against Germany and Austria because they had definite French support and probable British support, while Germany felt able to be aggressive because they believed that Britain had assured them of its neutrality.