We are being asked many times what requirements are needed for visitors driving here after December 31st, some people are saying that you need an International Driving Permit, we have asked for official advice and the reply is below, however if you do want to obtain an IDP you can get them from your post office at a cost of around 5.50 and they are valid for a year, we understand you will need to take your passport, passport size photograph and driving licence ( please note this is for visitors nothing to do with residents)
Official reply;

According to the official sources of the spanish authorities they state that the UK licence is valid in Spain for visits that are less than 6 months. 
For the moment we do not know if the IDP will be required but what we know is that the IDP only has a validity of 12 months.