Decent swell sizes are a rare occurance on the Med coast. You'd be lucky to get more than 10 surfable days in a year.
The surfable swells tend to happen during the winter, so you'll need a wetsuit.
There is a surfing video from mazarron here:
http://www.puerto-de-mazarron.co.uk/videos
I have seen them surfing on various beaches, bahia and the town beaches
There nice left hand point break just before you come into the town from isla plana.
They did try and hold a surfing competition in mazarron (but the lack of swell made it a bit farsical)