Peer pressure and bad culture. Low prices in chain pubs made drinking very cheap, particularly during the week where clubs would put on 2 for 1 promotions. If alcohol was rationed or prohibitvely expensive, which it simply is not I would not have afforded it.
What has pulling out of the EU got to do with Sharia law? Parts of Sharia law I quite like actually but its irrelvent here. Britain may well be outwith the EU sooner than you think. Maybe, it depends what the majority of her people want. However, the EU isn't the reason for our alcohol culture, although, back in the 70's before we were in the EU, my family tell me city centres were not full of these drinking dens, and booze was dearer relatively to wages. Perhaps the EU is to blame...somehow...