With respect to the blower speed regulator.
To find, with the glovebox removed if you look at the rear of the fan housing then look up and towards the centre of the car, you will see 1 brown and 1 red lead, these are the feed to the fan motor and a block with 5 wires which appears to go into the ducting.
remove the brown and red wires and disconnect the plug this will leave the reg which is held in by two plastic clips/tangs ease these apart pull the reg out.
The clips break easy and the reg can get stuck, I removed the blower housing and pressed the reg from the inside of the ducting. (recommended if its stuck as theres only 4 torx screws)
You can pick one up from a scrappy, I got one last week for £15.
Get one of as new a car as possible, will fit off a facelift. They are slightly modified, old type has vanes newer type has lots of posts, this will increase surface area and aid cooling and therefore reliability.
Only difference being if you have ECC then you need to get one of a car with ECC, same goes for if its just plain AC, must come off a car with AC.
Vx have a tech cure for fan speed running its on the Vx TIS, I'm at work at the moment, TIS at home will have a look tonight and post the info on this thread if you still need it.