http://ribworld.com/forum/showthread...argehouse+lane
If linky doesn't work , try a search for Bargehouse lane , usable only at high tide with a 4X4 .
It's the only one I know of on the Northern Bank of East London.
More info on Boatlaunch .
Codders , the PLA et al will tell you that they do want the Thames used as a leisure resource , but it's really not that easy to get on the water ( but well worth it once you do ).