Spanish maps are vague. What you get on google earth should be aboutr as good as it gets. Tourist information in Santander will have a decent enough map of Santander. For surrounding areas ... that's something else, I've no idea what's available in the UK.

If you want to go exploring a little in Cantabria (the province of which Santander is the capital) try looking for info on Comillas where there are a number buildings designed by Gaudi who designed the Sagrada Familia in Barcelona, there is Carbarceno which was an open quarry until they turned it into a zoo, the landscape is pretty surreal and the animals are out in the open, you need a car though. Santillana del Mar is is lovely little town, well worth the visit aswell. San vincente del Barco is a pretty fishing villiage just on the border with Asturias, it's probably most famous these days as the home of one of the Spanish 'Fame Academy' finalists who actualy went on to be relatively famous.

Santander is close to the Picos de Europa but I have not explored from the Cantabrian side.

Within Santander, the beaces of Sardinera are marvellous, the park La Magdalena is great. The nightlife area was around the area where the Fine Arts Museaum is located. The port area is nice aswell.