make sure you understand the system and don’t feel obligated to go to every little place on it. Even just going to the main places makes it worthwhile. Will say the Churchill underground WWII command center was great but we wouldn’t have known to go w/o the pass. Plan on 2 half days at British Museum. It would be easy to get burned out trying to do it all at once.
Taking the train out to North Hampton was really worth it along w/ Windsor the other direction. St Paul, London tower, Westminster Abby, The Globe, Piccadilly ( maybe see a show), London Eye (did this 1st thing to orient ourselves) were all awesome but liked NortHampton & Windsor best.

You’ll have a wonderful time.