Lunch happens late in Catalonia, 2pm at the earliest, so you might get a bit thirsty or peckish.
Older Catalans, however, will let you in on a wonderful tradition that solves this problem (though it has unfortunately been dying out a bit over the last few decades): fer el vermut, or the hour of the vermouth. Around noon, especially after mass on a summer day, men gather in a café or outside on a sunny terrace to have a glass of vermouth with a bit of carbonated water and lemon. With this one eats various canned preserves (olives, anchovies, artichokes, cockles) or simple fried foods — squid, patates braves (fried potatoes with a spicy sauce), or perhaps cheese and fuet (a type of cured sausage). This may sound similar to the Basques’ evening-time tapas, but at the vermouth hour one generally eats less elaborate snacks, and they’re not served on little pieces of bread.
While young Catalans tend to be ignorant of this tradition, they do sometimes have a midday, pre-lunch snack sans vermouth, especially on Sundays, called simply the aperitiu.