One of my favourite websites. There you can learn about English varieties in London listening to some of them. You can also record your own speech!
A page where you can research about Estuary English, which is widely spoken in London.
If you want to find information not only about London English but about other varieties, visit this webpage.
Information about what they call "the London standard".
A very interesting archive of the dialects of English.
Learn some nice Cockney expressions and surprise your mates...
A bit of language, a bit of history. Nice website.
An article about RP English.