I haven't personally changed a head gasket on a Rover, but have on a few other vehicles. If you are mechanically inclined, it really isn't that hard. ***EDIT I would go to the dealer either way****. Find a good mechanice anywhere for less money. Also when the change the head gasket, I would have them check to make sure the head isn't warped. I you have to shave the head, make sure you do both.
LR mechanice = $100 an hour, any good mechanic at almost any shop = < $50 a hour so you get twice the work for the same money.
Remember if they say they don't work on LR's just tell them it is a 1960 buick 215 motor with fuel injection....
*** I wouldn't go to the dealer either way too expensive*** EDIT