This looks like a total nightmare...

Just to add my bit, friends of mine who work in La Caixa have commented on this general theme that whilst up till now any building that had been built and not demolished by the council could indeed be legalised now the situation is one of zero tolerance.  Local councils may tolerate this and even give you the nod to go ahead with it but the final legalisation comes from Tarragona and they have apparently decided that after having completed all the POUM type plans around here nothing will get this legalisation from now on, even if the local council wants it.

YOu have to be so careful with all of this.  A non legal house whilst suitable for living has no legal standing in the event of the council building roads etc and also won't qualify for a mortgage if you want to re sell it and the buyers need one.