Most shops shut today as well.  I think they've made it a long weekend.  For general weeds you need Glyphosate (Glyfosato).  That's a generic name, not a trade name.  One of the major brands is Roundup but that's expensive and no better than the locally available generic ones.  There's another type that the locals call "Cappa" or similar.  That's a pre-emergent killer (as opposed to Glyphosate being post emergent).  Glyphosate becomes inactive when it touches the soil and so doesn't affect crops planted there afterwards.  Cappa sinks into the soil and should not be used where planting is planned for the next 3 or 4 years.  Glypho is safe for animals but not near water that might hold wild life (or fish).  As mentioned, Sol D'Ebre or any other co-operative will have it.  It'll cost you 20 -40 € for 5 litres (it varies over time) but that will go a very long way when diluted.  If you want any tips on using it, just shout.