Ok. If you get to London, it will be interesting for you...
London is one of the world's largest cities, but is fairly easy to navigate via public transportation with a little research.
The Tube is London's underground subway network. It was the world's first subway system and some of the station platforms were used as air raid shelters in WWII. It is usually the fastest way to get around town and Travelcards (available in 1 or 3 day lengths) will allow you to travel as much as you'd like for one set price. Also, children under 11 travel free after 9:30am on weekdays and all day on weekends.
London is famous for its double decker buses. Although much slower than the Tube, it is a very inexpensive way to see the city. One popular route is number 11, which will take you by St. Paul's Church, Fleet St, Trafalgar Square, Parliament Square, Victoria Station, Buckingham Palace Rd, and Chelsea. A one-way fare is just 1.50 pounds...compare that to the 20-30 pounds for the pricey tourist buses that will take you by the same sights!
Try to avoid cabs as the cities clogged traffic will almost certainly make it an expensive ride.
Thanks to www.onthecheaptravel.com