I think the (hopefully) eventual british focus tree should be the UK being focused on making their ties to their old dominions stronger, creating an alliance on it's own, or just making it so they can all join nato (the former would be if they don't get leadership, although they can still do it, but the latter is ONLY if they lead nato.) I could see argentina striking the falklands as something the british have to deal with, and possibly fending off their allies/previous dominions from invasion (america with canada, possibly china with australia and new zealand, etc.) It'd have a typical economic tree, but would overall just have the UK resurge as a world power.