I assume you mean the age at which you can purchase alcohol in Spain, which is 18, the same ast the UK. Spain in common with most European countries have a very relaxed attitude to alcohol, it is seen as a pleasurable addition to an evening out, not a reason to get as slaughtered as possible as quickly as possible, as the British tend to do. For this reason, children often enjoy a glass of wine with meals from a relatively early age, so a drink is no big deal, and so they don;t suffer the binge drinking culture of the UK. That said, the Spanish are keen on manners, and frown on loutish and loud behaviour, especially from visiting tourists. The police are less inclined to reason with drunken yobs than to make their opinions felt with a truncheon-and-head interface, and suggesting that a policeman 'has a go if he thinks he's hard enough' will result in him proving that he will, and he is, and he carries a gun as well! Drink driving carries very severe penalties, so if you are going, behave sensibly, respect the country and the people, and you'll be fine. Act like a Chelsea headhunter on a Saturday afternoon, and you will not be happy with the reaction.