I kind of think its crazy to leave the UK with large expensive THREE capital ships that you could easily sink and only lose your subs and maybe a plane or the battleship. At the very least I can see the value in trying to do the battleship retreat.
If you really wanted to convoy UK into oblivion, I’d plan on Barbarossa G3 or G4… buy the G1 bomber and carrier. Kill as much fleet as you can, retreat the German battleship if there is only 1 UK ship. 2 subs at Canada, ignore cruiser down south… G2 buy depends on if the battleship is alive but you need a destroyer and bombers and 2 or more subs. 1 sub is for sz 125, the destroyer for the Russians, 1+ sub joins the bombers in killing anything at Gibraltor.
I’d also consider taking S. France on G1 so on G2 you can build a carrier and transport there, which protects the Italian fleet and can help out with ground forces. Puts more pressure on UK in Africa to push their spending all over, not concentrated.
By G3 you’ve got an idea whether you can get away with convoy sz 109. Maybe the German carrier heads north after turn 3 if Italy gets things under control quickly.
Or if things don’t go Italy’s way, they can buy subs to hit things off Gibraltor, too.
