As it's widely acknowledged that Britain fielded the best equipped and most modern military formation in 1940 Europe in that shape of the BEF, I take it you are referring to a wholesale expansion of the British Army both in size and equipment? IMHO that would have been impossible; not so much counter-factual as non-factual, bearing in mind the equally essential investment in both the RN and RAF throughout the thirties.
The fact that the BEF was too small to save France all on its own at least meant it wasn't doomed to attempting that task, and Gort was able to take the decision to withdraw to Dunkirk.
I think it is fair to say that the RAF's pre-war procurement policies were responsible for the winning of the Battle of Britain, and set the foundations for the the later hammer blows delivered by Bomber Command and the US 8th Airforce (to an extent). How many airfields sprang up across England in the thirties? Whilst the Whitley, Hampden and Battle all disappeared from the order of battle, the Wellington soldiered on throughout the war, and the Lancaster and Halifax were both the result of pre-war design requirements.
As to the utility of strategic deterrents, I think you may have stretched your metaphor. Remind me, how many times has the UK been nuked?
I am not too sure about the Lancaster being the result of a pre-war design requirement.
The Lancaster only came about because of the terrible engine problems of it's immediate predecessor the Avro Manchester.
It can be argued the had the Rolls Royce Vulture Engines been a success the Lancaster may never have been built.