Often wondered why there aren't more alternative-history movies....

Here's one I always wanted to see - It Happened Here, from 1964.

Never even knew there was a movie of Fatherland, one of the more recent fictional stabs at that if-Hitler-had-won hardy perennial.

 

 

There was a late 70s TV series - An Englishman's Castle -  based on this scenario, but the idea was that things wouldn't actually be that different. So Germany presided over a sort of European Community, a united Europe. The UK was beset by terrorism, just like it was in the 1970s, but the terrorists were the remnants of the British Resistance and the general public is getting weary with them.