Also wondering about this but can't advise as I haven't actually done it! Are you taking the ferry to Bilbao/Santander? I would love to do this but would have to first take the ferry to the UK from Ireland and then on to Spain so a fair bit of driving for us.
hi, yes, we're taking the ferry from Plymouth to Santander, it's a more or less 24 hour crossing , depending on what day you go. We're taking the Sunday-Monday crossing and arrive about 12 noon. From then it's a couple of hours tops to the Picos ( I reckon) so definitely doable . We normally go to France /Italy or Switzerland and can usually be a good 8-9 hour drive, so I'm looking forward to this one.
We did the same trip a couple of years ago and saw dolphins on the crossing !
We're also going on the Plymouth- Santander ferry to camp in a few weeks! Not to the Picos, we're going to the Pyrenees, but we looked into Picos campsites too. I camped there years ago at a nice site in Arenas de Cabrales which is a village in the middle of the Picos, it has streams and mountains around, I think it would be good for children. No pool.
It has decent loos and showers, nice little bar/restaurant/ takeaway, and direct access to a good size river for paddling , skimming stones,. We camped right next to the river which handily covered the traffics noise from the adjacent road.
We did a recce of this site elcarescamping.blogspot.co.uk/p/english.html which was lovely and would definitely try in future if we were to go back. It is much higher in the mountains a good hour up windy mountain roads from Potes (the main town in the area) As its so much higher , it was definitely cooler as well, so warmer gear needed!
We also stopped at these sites
Near Madrid: www.campingelescorial.com/en/ - ok, but v big. Nice 'free camping' area as well as the typical regimented rows. Plenty of shade , decent pools and plenty of activities ( tennis etc) if you want that. Was roasting hot !
Direct on a lovely beach with lots of sand and good waves for jumping! Decent sized shady pitches, ( we had a beach front one which was fab, but a bit windy in the afternoons) . Good loos/showers/shop/restaurant etc.
Hope these help anyone else looking at Spain for next year.