i know you are very good player, so tell me what wrong with my ideas
It wasn't for me but I'll tell you just one: Brits would be the very worst faction at dislogding enemy units of building without UC flamer in the early game. Making this option fuel dependant would be just unfair. Give them another anti garrison option, then you can give a fuel cost to UC.
Btw. OKW was bad at this too, because of that they got the flame nade one day. This insn't fuel dependant either.