Go to Santander, a few miles west from San Sebastian, and i can thoroughly recommend these guys:
ECS Santander
Phone them up and ask to speak to Nacho (No kidding, that’s his real name!) he speaks good english. The surf school is on Somo Beach, across the harbour from Santander town.
I used to go to Somo beach twice a year (Easter & late summer) and had lessons with Nacho for about three or four years running. Nacho is the best instuctor I have come across (And i’ve tried a few!). He can also hook you up with acommodation in Somo if needed.
For beginners, Somo beach is much better than anything San Sebasitan has to offer. It is a very long curving sandy beach, with a shallow gradient. If there is any swell at all, Somo will catch it.
If you are arriving from Santander (Bus / train station), go to the harbour and catch a little ferry over to Somo beach (get off at the SECOND stop). If you are driving, just go directly to Somo.
If you need any more detail, just mail me and I’ll help you out (email in profile).
Cheers!