There is no longer a requirement to exchange your UK driving licence for a Spanish one if you intend to live in Spain. You can continue to use your UK licence until it expires providing that you are reachable at the address on your licence.
Your UK licence must be one of the EU style licences and preferably the new photocard licence. We suggest if you still have an old style paper licence that you exchange it for a new one before coming to Spain.
A point to consider is that, if you become a resident in Spain, the DVLA expect you to return your UK licence and will exhange it for a certificate of entitlement which you can then swap in Spain for a Spanish licence. Another example of what someone giveth, someone taketh away.
When driving in Spain you must carry in your vehicle a fire extinguisher, reflective jackets, spare set of bulbs and tools to fit them, spare tyre and tools to fit, 2 hazard triangles and an approved type First Aid kit. It is an offence to use your mobile phone when driving. You should also be aware that radar detectors are illegal in Spain.