In the film "Munich - The Edge of War", the ending of the film talks about how the Conference bought the British and French time to build up for the war. However, as we see early in the war, the Allied performance is lacking. The Fall of France, the evacuation of Dunkirk, the failed Greek expedition, several defeats in North Africa. Furthermore, as far as I know, Chamberlain and his government were hesitant to implement rearmament. British and French forces performed relatively poorly, and as we saw after Dunkirk, the Brits were really struggling since they didn't have any major stockpiles of rifles to call on. This has led me to believe that this statement is a false one.

So here is my question. How important was the Munich Conference? Did the time it bought really have that much of an impact on the War? And how much did the Allies actually build up in the year or so between the Conference and the outbreak of hostilities?