For a superpower see a timeline called rule Brittania on an imperial federation.(it's very good)
Post 1945 the uk can do very little,but say it pursues a more French approach to decolonisation-it could itergrate current overseas territories,Malta,Hong Kong,British West Indies, Aden,maybe Singapore,Guyana,Papua new guniea(more difficult since its Australian)Newfoundland ,Belize,Cyprus,Fiji,other pacific territories. Very difficult,but possible if things go a certain way : Rhodesia,Suez Canal Zone and Ceylon,Zanzibar??. Even if that doesn't happen with just a few more territories and a few favourable trade and military deals with Canada,Australia,a non apartheid South Africa and New Zealand public perception may be that the commonwealth is a strong successor to the British empire,which still survives with a sizeable number of outposts around the world. (albeit in reality dependent on the USA). If the uk comes out of ww2 slightly stronger,the USA follows through its agreement with the the uk in the Manhattan project and suez is avoided a different approach may be taken to decolinisation and importantly without suez the British publics pride in the empire will still be as it was in 1945,which is important as if they wish to preserve (parts) governments will deliver,with more investment in the smaller colonies. Also a less messy withdrawal from India may help.