I've done a lot of travelling in the North of Spain and I love it!!
Summer's not the best time to go for waves, but here's some spots that have been working in the summer on a small swell:
http://www.wannasurf.com/spot/Europe/Sp ... index.html
http://www.wannasurf.com/spot/Europe/Sp ... index.html
http://www.wannasurf.com/spot/Europe/Sp ... index.html
http://www.wannasurf.com/spot/Europe/Sp ... index.html
http://www.wannasurf.com/spot/Europe/Sp ... index.html
My favourite spot is Liencres and always had a wave when everywhere else was flat .There should be a regular bus leaving Santander...............yeah I just looked, and theres one every half an hour
There's a little beach break in Santander called El Sardinero which might be worth a try.
Somo is a ferry ride across the bay in Santander and gets the swell from the west.
Los Locos is in a town called Suances which is pretty easy to get to by public transport and there's also a break called la Concha in Suances
And the two places in the Pais Vasco (Bakio and Zarautz) are right in the middle of the town, so they'll be really crowded in the summer, but Bakio's a loveley place.
Another spot that I've found working in summer is Sopelana in Bilbao.......you should have no problem getting there by public transport cos its on the Metro, or there's a campsite nearby.
Another good campsite is in Mundaka........the views from the restaurant are amazing.
I've never seen Mundaka working, but I've always stayed in Mundaka and gone to the next break which is Bakio..........I dont know if theres a direct bus, but you mught have to change in Bermeo
Here's a link to the campsites:
http://www.vayacamping.net/map.asp?lang=es
You'll have to book Mundaka in advance cos it's always full in the summer.
Have a good trip!