Hello Nick,
Not sure about the British version vs. the "FOX" in US use, but there is a Revell kit that is specific to the NBC version...perhaps you are already talking about this kit? IF so, it is very basic, period. If the British version is the same as the US version (and not hte same as the German version) and you can get a copy of the Concord book on US Softskins in Military Service, they have better detail shots of the vehicle and some of the details needed.
I built the kit for a friend who served on them and only did rudimentary detailing to it beyond making it US Specific. This included adding the sampling ports in the rear and some other small details, all located in the areas specific to maikng the US "FOX" version. Hope that helps a bit!