Lemme reword what I meant, I can't see Germany beating the UK but I do think they could have done a hell of a lot more damage. One thing that is very often over looked is the length of the war in my opinion, for a human, probably around 12 years old or higher the germans couldnt have convinced them to be "Germans" But since the germans took france poland etc by 1940, if the war would have lasted untill 46 or 47, which it probably would have with a 1 v 1 with UK/Germany (italy was sort of pointless...I remember a quote i saw by Mussilini, saying he didnt want to fight in the war but he wanted to kill 2-3,000 french and be on the winning side) that means 10/11 year old french/czech/polish/danish/belgian/dutch/norweigan men could have been raised to become German soldiers, which would have easily doubled Germanys army, that is something overlooked by a lot of people. therefor i think on a 1 v 1 Germany could have atelast got into the mainland of UK, but I do guarentee you the minute German soldiers got close to taking the UK mainland we would have stepped in, becuase at that poing if you guys went, it would be a 2 v 1, us vs japan and germany, which i guarentee you we didn't want.
Anyway overall I don;t think you guys could have won, but I can't say for sure if you would have lost, probably just a stand still, Hitler probably gets assasignated by some german, and without Hitler the wars over in a blink