Northern Portugal is very mountainous and rural and unless you have a vehicle pretty fucking inaccessible... If you want the classic urban squat experience you'll be looking at Lisbon and possibly Coimbra...
I used to visit the Coja / Arganil / Goish corridor which - if you look on a map - is pretty much the centre of the country, about 50 clicks East of Coimbra... that area is full of expat British / Dutch / German hippies and travellers of all flavours - but again very rural and remote and a pain without your own transport....
finally, while I know nothing about it but I've heard Galicia and NW 'green' Spain has got a kicking punk and anarchist scene..