Depending on the parts determines where you buy them, things like alternators, water pumps and the like buy from a junk yard or a place like AB.
Brake light switches, lights bulbs and other common does not cost alot or leave you stranded type things you can buy at the autoparts store.
Belts and hoses get local, other disagree but I buy my brakes local.

Here are some things that MUST be done to a Rover every 2 years and is a good idea for any car.
Change the coolant, brake fluid, diff and transfer case and transmission fluids, it is cheap insurance.
I last did mine in 2007, so now its 2009, time to change these things, does not have to be exactly 2 years, just rough about.

 

NOPE, they have stuff that will fit but not give you what you want.
Try Atlantic British, Rover Connection or DAP.
Before you go and order, pull the wheels down, especially both of the fronts, you may need more then the usual brake parts, see if your calipers are dragging.