Dont think this is going to help much…
Breakdown cover in Spain is normally included in the Spanish Car Insurance relating to the vehicle, under the heading ‘Assistencia de Viaje.’ If you have Spanish insurance on the car it might be worth checking it out.
Is the car still on English plates? Is the UK road tax and UK MOT up to date? Do you have an address in England… If the answer to these questions is yes then there is no particular reason why the AA or RAC shouldn’t give breakdown cover for the car and include European Cover.
However… If the answer is no regarding UK Road Tax and MOT then you cannot legally drive the car anywhere in Europe anyway… so the question of breakdown assistance would be irrelevant anyway. Again if it is on English plates and the tax / MOT is out of date, even if you make it to Bilbao unscathed, you can expect some serious problems / questions if you encounter a stroppy Customs or Borders Agency inspector when you arrive in Portsmouth or Plymouth.
It’s a horrible Catch 22 situation… can’t get road tax without an MOT, but can’t legally drive to an MOT station without road tax.
Not much help!