Having a car is actually an advantage. If you would need to rent a van or otherwise procure one just to move, it could be too expensive but since you already have a vehicle, you can just pack your stuff in it and drive to Spain (surely you have got a few other things than your PC you had like to keep…). That's the way I moved between various EU countries and it always worked quite nicely.
There is usually some paperwork and, in your case, possibly some right-hand drive/left-hand drive issues but importing a car from within the EU is typically not that complicated. If you owned it for some time and import it as part of a move, it should also be tax-free. So that would take care of the what-to-do-with-the-car issue at the same time!
Alternatively, if you are certain that you will go back to the UK in two years (and not stay in Spain or move somewhere far away), you might also drive back with your car for your next holiday and park it somewhere with relatives or something (do beware that after you become a resident in Spain, you are probably not allowed to drive a UK-registered car there anymore).