Hola - Yes I know what you mean - maps are not as readily available as in the UK but the good news that they do exist.
Visit http://www.ign.es most of it will display in English. Click thru and you will find the CNIG section which lists all of the locations - mainly cities - where you can buy maps. Also try tourist info centres especially in walking areas.
I do not know your nearest city bit here is the Granada address:
C/ DIVINA PASTORA, 7 y 9, LOCAL 15
Enjoy your walking - I am hoping to do a bit this autumn in the Alicante Marina alta area with my new GPS gismo a local Spanish paper is giving away free routes every Saturday at the moment.