Herod,
Undoubtedly those months in 1940 were absolutely critical and we were at our most vulnerable. One can make a valid case that we were saved as much by Hitler and Goerings blunders as the outcome of the Battle of Britain.
But let's not have any of this "poor little England stood all alone" nonsense. We had massive resources both material and financial, but your point about those 1940 months remains valid.