Heck, the National Government kept offering to give Germany some of her African colonies back, so its possible it could happen that way round - eg Chamberlain gives a guarantee to Poland earlier on, Hitler is persuaded not to advance his plans there, Chamberlain gives Germany a bunch of colonies, after Chamberlain's death, or retirement due to ill health someone of his ilk takes over, Hitler tries the Polish bluff and it seems to work, but then Britain wakes up and war starts - maybe in late 1940
Best Regards
Grey Wolf