There are several good reference pictures of the LandRover with WMIK on the UK MOD site :
http://www.operations.mod.uk/telic/photo_gallery.htm Look under the operations on land and the preparations pages.
With regard to the kits available in 1/35 I know of the following :
Tamiya Rover 7 ambulance
Tamiya SAS 'Pink Panther
Italeri SAS Combat Car
Revell LandRover 109Series III (also released in a hard to find civilian version I believe)
Accurate Armour LandRover Wolf series
The 2 Tamiya kits share a common chassis sprue with each other with seperate sprues for the individual body work. I have one of each (got them on Friday in fact) but I have only given them a cursory look over.
Likewise the Revell & Italeri kits share common sprues with 2 sprues being common and each kit having a smaller individual sprue of variant specific parts. I have 2 of the Revell kit and 1 of the Italeri.
Eduard make a Photo Etch set for the Tamiya 'Pink Panther' and this set includes several parts that will be usefull for all the kits.
I am presently building a Revell kit, it is configured for Left Hand drive as opposed to RH drive in all the others for which Revell have made minor mods to the moulds for steering rack but I needed to tinker with the chassis locations to accept this new part.
My interest in LandRovers has been spured on by my neighbours recent purchase of an Army Surplus LandRover 109. I don't have the money to get one of my own but I can have a few 1/35 size ones and I won't have to pay the Road Tax :-)