I disagree with you that British Rap/HipHop is very American. Firstly there is alot less swearing in UK stuff. Also every other word isnt joint/nigga/bitch/hoe/gun etc.
A small list of UK artists for you
Braintax
Foreign Beggars
Natty
Jehst
Klashnekoff
Rodney P
Skinnyman
More details about (most of) them are on
www.karmadownload.com. Direct link to UK HipHop section
http://www.karmadownload.com/genre/?13. Enjoy.