Posted: Mon May 6, 2019 8:22pm
Assuming you're talking about a UK licence then whichever way brexit pans out the near universal advice is to exchange to a Spanish licence at the earliest opportunity.
Providing you present a valid licence and proof of address, which could be in Spain or UK or elsewhere, hire companies are not generally too bothered about where you are actually resident but that means it could become possible to satisfy a hire company with a UK licence and drive away in a car only to be stopped by the police and told that your licence is not valid, an accompanying IDP will make no difference as it's no more than a multi language translation of a licence.
Seldom has such a mostly worthless document been so badly and misleadingly titled!