✔ 最佳答案
Actually you just need to spend 1-2 days for the City tour: Trafalgar Square, Tower Bridge, St. Paul's Cathedreal, River Thames, Westminster, Downing Street 10, and the Palace. Take the Tube (underground railway), it is very convenient.
Spend 1 day to Cambridge (1 day return coach tour), 1 day to Oxford (1 day return coach tour), 1 day to Greenwich (1 day return boat tour).
One recommendation if you are interested in musicals: My Fair Lady and Phantom of the Opera, a lot cheaper than in Hong Kong. In fact, you can find a lot of theatres in London for showing musicals every night, it's worth seeing.
參考: myself, self-travelled to London before