Is there anywhere in the centre of london, or near, that you can leave suitcases or bags for the day? I'm going for the weekend but our flight home is not till 11pm and we have to leave our hotel by 12pm. It would save us from carrying our stuff everywhere.
ring and ask the hotel is there a facility for left luggage after all you are a paying guest, if not use the most convenient large train station for you, preferably one that you can collect and then get the train straight to the airport.