In the UK how old do you have to be to buy alcohol?

-I'm talking about anywhere, not just in pubs but in shops too. I think it's 18 but a girl told me it's 21.Eighteen is the legal limit for purchasing alcohol in the UK. Five is the minimum age for drinking it in private. some establishments have a 21 limit but that is their commercial policy, not the law of the land.
To purchase alcohol, you must be 18 years or older, both in a shop and at a pub or bar. In an establishment which serves food, someone 18 or older may purchase an unfortified alcoholic drink (ie wine, beer, cider, perry) for someone between 16 and 18 provided it is ordered with a meal. You may consume alcohol at home from the age of 5.
18
n most place now the age is 18. but in some well-known stores, their limit is 21 or even 25

no. just no.
you can be any age
The girl who told you that is a ditz. It's 18.
50
You have to be 5 years old