After a little investigation, it appeared that my heater resistors had gone (apparently very common in Rovers), thankfully this is a piece of cake to fix. Went on ebay and ordered a REZPAX repair kit for about £7. For anyone that has this problem, they have an instructional .pdf that might be of some use. Check out the link below.
How to fix MG ZR / Rover 25 heater resistors
To get at the heater resistor pack the glove box had to come out, so that was the first job. Then out with the resistor pack. This is what I was greeted with. It's not very clear in the second one, but you can just make out that the nearest resistor is split two coils from the left end.
Next I snipped off the old resistors and broke out the new set. (I forgot to take a picture of the new set not attached so I nabbed REZPAX image, my kit looked identical to the picture). Then just soldered them on. Refitted it and jobs a good'en, all settings work fine. Another plus is the resistors look a little better in quality too, so shouldn't go again.
