I dont mean to be rude at all but the best mix for colours for british army stuff is humbrol khaki drab 159 and 33 black. Unless u personally use a challenger 2- (which you may do) then I doubt that grey is correct. If you put a kit next to a real land rover wolf the you can see that 159 and 33 match the British army paint colours pretty well. The opfor scheme is like 93 desert sand and 159.
Hi there if you look closely at the field grey when it is applied then it looks more green than grey. I have a friend who is a former tank driver and he told me that this is the nearest he has seen on a model.