Here are some passages from two chapters of Churchill's memoirs to start your research.
He regarded the Polish action in seizing their chunk of Sudetenland as "shameful" and that they were like German "vultures" on Czechoslovakia's carcass; and "grovelling in villainy".
France's leaders were even more vicious in their opinions of Polish actions in 1938. Best you find and read them in the original French if you're really interested.
Which proves nothing, fact is in 1939 France was set for a defensive war.
Churchill's wasn't more kind to Russia, but you know that.
But I'm curious, what had Czechoslovakia done according to Paul N. Hehn to be betrayed as they were by France and the UK ?