Ian,
a mate of mine works in a range rover dealership.
I am guessing you would like him to connect up the diagnostics kit to your car. Chances are this would require you to get the car to him, unless it is something he can perform using a laptop and appropriate software.
FYI he lives in Addlestone, so not far from you.
I will ask him if he is prepared to have a look when I see him later in the week.
Please send me an email on Wednesday and Thursday to remind me as I am likely to have forgotten by then !
Cheers,
John.