World Ju Jitsu Federation
The WJJF is an organisation
a particular style of Jiu Jitsu
(both spelling variations have been used within the style).
The WJJF in its present form was founded by Prof. Robert Clarke (9th Dan) around 1977, based on the Japanese style Hontai Yoshin-ryu.
Headquaters for this style of Ju-Jitsu are in Liverpool, however there are clubs throughout the world (so I have been lead to believe). Anyways there are several clubs in the country which are usually friendly enough.
A link with information about the style follows: http://www.holt3.demon.co.uk/ .
This is not the official web page but gives much more info. about clubs and has some pictures, without trying to purely sell you all manner of things.