Hi Paul, you may have moved on in the 6 months since this was posted but I found an article for you here that might help.
http://www.consumer.es/seguridad-alimentaria/normativa-legal/2015/07/14/222193.php
They seem to be working on new legislation to cover microbreweries, or were last summer at least. Not aware if it passed.
For legal regulations in general, you probably want to use the word "normativa" in your search. And they seem to be wanting to regulate microbreweries under "fabricación artesana."
If you get set up, let me know and I might drop in for a caña.