✔ 最佳答案
You can check the below website.
http://www.visitbritain.hk/destinations/city-guides/london
I would suggest you to buy London Pass and Oyster Card (such as Octopus card in HK).
Below please find my travel plan of London in 2006 for your reference.
Day 1: London Eye, Thames River Side, HMS Belfast, London Bridge, Tower of London
Day 2: Kensington Palace, Sherlock Holmes Museum, St. Paul Catherdal, St. Paul Cahterdal Square, Jewel Tower, Banqueting House, Wellington Museum, Wellington Arch, Backingham Palace, Leichester Garden, Covent Garden Market
Day 3: Hampton Court Palace (the garden is really beautiful!!!), Winsor Castle, Winsor Castle Square
Day 4 - Day 6: Liverpool & Manchester (visit friends)
Day 7 : British Museum, Westminster Abbey, Big Ben.
I used 3-day London Pass for Day 1-3, then I visit the museums and palaces. British Museum is free for entry.
As you have 7 days in London, then you can 2-3 days to travel Oxford or Cambridge. If not, then you can purchase 6-day london pass and select more attractions in London such as Madame Tussauds, Shakespeare Globe Theatre, Royal Mews, Kew Gardens, etc.