There is nothing new in what you say about the Soviets not wanting to fight another war in 1945. Still, that didn't stop them blockading Berlin in 1948 - and that came perilously to a shooting match at times.
Quoting from Keenan and the like is pointless. Most wars start from two causes: a pre-existing tension [such as France Germany in the 1900s] and an accidental trigger - in that case, the assassination of Franz Ferdinand.
Thus in the Cold War: the pre-existing tension, and some one doing something stupid at Checkpoint Charlie.
As for defence costs which you go on about - most of that was spent garrisoning Germany and the Empire, very little on the Cold War. Macmillan was aware of the costs - which is why he used nuclear weapons as an excuse to abolish National Service.
Now let's have some concrete, primary, evidence for the RAF not having nukes before the 1960s - not airy speculation.