Yes as Jack says its a looooooooooooooong drive. We did it last year From Roscoff right down the Atlantic coast, (loads of nice Aires, some crap ones) through Bordeaux, & Biarritz (which has the smallest most packed beach I have ever seen, sardines have more room!!) and on into Spain. Although we only stayed briefly as our main plan was to drive the full length of the Pyrennees which was beautiful & scary at the same time!
We would love to motorhome in Spain but not for a few years as we are planning our main holiday next year to tour the south & west coasts of Ireland.
God luck anyway, the weather is nearly always good in Spain I suppose, it depends how long youve got to tour. We were lucky as we had a full month to do it last year.
John & Emily