wheelchair accessible accomodation in london.

I am bringing my family of 4 to London for 10 days in London.My 13 year son is on wheelchair fully.I have read Rick Steves book on easy access europe and it is informative.Need recommendation on accessible hotel in london,considering difficulty in transport.We are also planning to spend few days outside london like in Bath,Oxford or Stratford.Are those towns handicap friendly.Thanks for your help