> I had to look this up but apparently the UK doesn't either.
There are a few city-wide regulations in Scotland that prohibit it, possibly in other parts of the UK as well, but there's indeed no such national law.
In Poland, drinking in public space (with some exceptions) is forbidden. Sometimes police will issue fines even for “intention to drink” if they see a person with an unopened bottle of beer.
To my knowledge, in Spain you're not allowed to drink in public(?) Whether or not people/the police care seems to be an entirely different matter, though, and also depend on the city/region.