@simon33, certainly the game works with two UK economies and there are lots of things to enjoy about the way that pans out. I’m not saying the game is broken, just discussing alternatives.
One advantage to the unified UK economy that I noticed in the SiredBlood variant is that the Allied player has much more control over their level of risk with respect to Sea Lion and India Crush. Some people (like you?) complain that the UK has to buy 100% infantry on turn 1 to fend off Sea Lion. Other people complain that India is doomed and that the Allies have to make massive, urgent efforts to contain Japan, like maybe a turn 2 Persia factory that pumps out mechs for India. So if you can slosh your economy around, then you can choose which of those two ignominious fates you suffer.
Want to play aggressively in the Atlantic? Build 10 infantry in London and a factory in Egypt; go crazy. Want to play aggressively in the Pacific? Let London go, drop 2 mech + 2 tank in India on each of UK1 and UK2, declare war, and go for a Yunnan stack. It leads to more variety in terms of the opening positions that you can reach, which I like.
That said, I hear you on getting Canadian fighters to Moscow. If you’re not playing with my Supply Crates for lend-lease, and there’s no Sea Lion attack, then Canada could have little or nothing to do.