My personal view is that for a variety of Luftwaffe, Kreigsmarine, Wehrmacht, principles of war and geographical reasons - the Germans couldn’t have invaded the UK. Nothing quite as irrelevant as historical conjecture however.
What they probably could have done is win the engagements of what is now referred to as the Battle of Britain.
The fact that they didn’t is (speaking as an aviator of the dark blue variety) down to the performance of the Royal Air Force which was magnificent.