Germany winning against the UK is... a fantasy nothing less. The Battle of Britain caused severe losses for the Luftwaffe, Germany could never really recover. The naval power of Germany was... well pretty much second rate. Italy fielded more, and arguably even better ships, which was more hindered by individual stupidity and faulty quality control. Germany was never in the position to invade the UK. Even more so, after the losses at Norway... 1 Heavy Cruiser down, 4 remaining. 2 Light cruisers down, 4 remaining, approximatly half the destroyer forces down.... And we still have the issue, that Germany had only 1, battleship, that could effectivly fight against british battleships and battlecruisers. Scharnhorst and Gneisenau could not with insufficient armament. You do not get naval supremacy, to be capable for invasion with 1 battleship, 2 "battlecruisers", 4 heavy cruisers, 4 Light cruiers, and some destroyers, against 11 battleships, 3 battlecruisers, 15 Heavy Cruisers 32 Light Cruisers, around 65 destroyers, and 4? if i remember correctly aicraft carrier. No naval supremacy.. no invasion. Insufficient submarine numbers to starve the UK..
Even after Italy binding some forces in the Mediterranian... not enough.