Because the med fleet will be blocked by a Russian sub, Germany, at most, can attack UK with the following:
6 infantry, 6 armor, 6 fighters, and 1 bomber.
I like the 2 FTR, 3 INF on UK1 myself so that isn’t that bad a battle to fight really.
7 INF (2 UK Start; 2 US; 3 UK1 buy)
2 RTL (1 UK, 1 US)
2 ARM (1 UK, 1 US assuming SZ1 TRN sunk)
5 FTRS (2 UK, 1 US, 2 UK1 buy)
Take the Bombers as 1st round casulties and you aren’t too bad.
Moving the UK BB and TRN and the R sub to SZ6 will draw off some air power as Frood says it is aprox. 78% for the UK/R in the naval battle with just 2 subs and a Des.
One of those things you shouldn’t feel too bad about losing though.