Field - thanks for asking.
To me, finding a mechanical method that takes out the UK, guaranteed, feels like a cheat. I’m a little bit of a purist, and I feel that Barbarossa is the natural order of things.
It then becomes a question of… do you see this game as a boardgame (just like any other) to be conquered and won, or a historical reenactment to be played better than the actual war was waged? That’s a major philosophical question for players of this game. It isn’t a terribly serious one, unless you think that A&A is serious fun… which I do.
So, I always purchase two transports on G1, to create the appearance and threat of Sealion, which forces the UK to purchase accordingly, and slows them down in Africa.
If the UK player defends London properly, I then turn all attention to the East… an economic war against the UK (strategic bombing/naval throttling in SZs 109/103), and a methodical dismantling of Russia.
If the UK player decides to leave London less heavily defended, I’d go ahead and put on a full-scale assault on London. I happen to play regularly against a person who always defends the UK against Sealion.
My answer, then, is to posture for Sealion - always - and from then on act based on the actions of your opponent.