Huge butterflies very rapidly. The first major ones would pop up in WWI, perhaps with Churchill gone, there would be a better invasion plan of the Ottoman empire instead of Gallipolli.
Its not at all obvious that our WW2 is going to happen.
Churchill was heavily involved in WWI, with British politics, with post WWI British governmental finance and defense spending (didn't he originate in the 20s the 'no war for 10 years' rule that he criticized in the 30s?), with the Arms and the Covenant movement in the 30s . . . shuffle all these around and you may get very different results.