we had to abort a trip to northern Spain last year (missed the ferry due to accident on motorway ), but we were supposed to be heading to the Picos de Europa mountains which could interest you.
We've been to this part of Spain twice recently and love it. The Basque area is absolutely fascinating and if you go to Bilbao the Guggenheim is a must. The seafood in this area is excellent, and try pintxos, the Basque equivalent of tapas. The coast is fantastic with wonderful clean sandy beaches, very popular with surfers. Sites we stayed at are Camping Itxaspe, east of Bilbao, and El Helguero near Comillas. (We've also stayed at Ribadesella and Luarca, further west.) Sorry, I'm not clever enough to put links on but there are reviews on this website. As Pitchperfect says the Picos de Europa, just a short distance inland, sound right up your street. We visited them from the coast, but there are some campsites right in the Picos including one in Potes. I don't know what the site is like but Potes is a lovely little town right in the heart of the mountains.
------------- Il vaut mieux vivre ses reves que rever sa vie
We'll second what the others say - go to Santander and then west to the Picos and beyond - you don't need to travel far south, the mountains are very close to the sea. Comillas is a good starting point for the Picos and westward but Bilbao and Guernica are good places to visit to the east. No great luxury in any of the campsites we saw but plenty of open spaces.
Might be a bit late, but we did exactly that last year: Portsmouth - Bilbao and then to Potes in the Picos. We stayed at Camping La Viorna just outside Potes. A nice, family site with a pool, and stunning views.
We then went to Mundaka in the Basque country, and stayed at Camping Portuondo. This was less of a family site, and more of a 'cool young teenagers' site. It was still relatively quiet, but didn't hsve quite the laid back feel we were looking for.
Can definitely recommend Picos Mountains though. Potes is really lovely and there are quite a few really nice campsites round there.
Good luck!
Don't forget to leave a review of the French and other European campsites you have visited!
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets