British lack of mechaniziation

With England being an important military and political power in the world, why did they not take this opportunity to improve their weapons and arms after WWI? Yes, they controlled areas such as Ethiopia that did not have current weapons but they should've realized that only one armored division was not capable enough of protecting their country. If the British had been able to better protect themselves in 1939 when Hitler was beginning to take over Europe, do you think he could've been stopped sooner or was it just inevitable?