Germany can win in the following way:
-Germany continue to bomb British airfield despite Churchill trying to trick Hitler to change his target.
-I believe some tanks are able to travel on water, since most british ships are on the north side of the country, tanks can land on the south side of England with the protection of germany navy and fighters. The Objective for those tanks are to finish off shore defense and let panthers tanks to went ashore safely, then Britain is basically finished.
-With Britain falling in to German's hand, Americans would be unwilling to attack Europe in a short time, that gives german the time to build heavy defense on England, while starting to invade Russia with better preparation