We will be arriving Sunday by 10 am and have tickets for a show at 3pm. Jet lag and probably not much sleep-and won't be able to check into the hotel till 2pm anyway. What's the best thing to do till the show? We also have monday as free time, planning on Tower of London that day. Ideas? Thanks!
And how close is the theatre to where you will be staying? Coffee sounds like a good idea. Personally I'd store my bags at my accommodation and then head out to where ever the theatre was located and explore that neighborhood. That's the beauty of London, it's diverse neighborhoods. Enjoy the show and London.
Between passport control and the train from Heathrow (assumption), you'll be lucky to be at your hotel by 12:30 or 1. Your room will probably be ready. I doubt you'll have much free time before you need to be at the theater. I agree with the prior post to walk the neighborhood. That will give you body a chance to get oriented to the time before you walk into a dimly lit theater. Be at the Tower early. Monday's are the slowest days but it's still busy.
I'm pretty sure you won't have much time to sit and fret. Odds are your flight will be about 30 minutes late. Allow an hour to get off the plane, walk through the airport, perhaps retrieve luggage, queue up at passport control, and get out of the airport. About another hour to get to your hotel, which puts it at about 12:30. If you can't check in, leave your bags there, go have lots of coffee, then find a cab to the show. Then let the jet lag take over.