If you get a chance, read this
book, it will enhance the trip. I was there about 15 years ago and had a great time. You guys will love it. I agree with GD, a trip out to stratford and stonehenge is well worth it. I enjoyed watching the bus driver navigate the roads in and out of London without hitting anyone, it's much more entertaining when you are in something big, and don't have to worry about it. One of my favorites was to go down to
Greenwich and visit the prime meridian, and see Harrison's clocks, along with the
National Maritime Museum.