Yes the fluid has started leaking it's goosed. I have spare one but it's the later version. If yours is the later one it would fit, early and later cannot be interchanged.
Sounds expensive
I you have the later type (CTB100220L), there may be no adapting atall. The MG/ROVER part is CTB100220 - without the "L". Looking at your photo., I think that you have the later one. I have an MG/ROVER part here, as a spare, if you need some details.
Not on a P reg Range rover he doesn't. The later type is 2000 and on it has a different windscreen mount than the early one and cannot be swapped over. Range Rover 2 Rear View Mirrors at www.rimmerbros.co.uk