Sorry, I stand corrected. I don't think there is a restriction for playing but these seem to be the rules in England and Wales.

Q: At what age are children / young people allowed into pubs?

Currently, if a landlord has a children's certificate, children under 14 are allowed into a pub, if accompanied by an adult over 18. If the landlord does not have a children's licence, under 14s are not allowed into the bar area of the pub. Under the 2003 Licensing Act, children under 16 will be allowed into a pub, but must be accompanied by an adult aged 18 or over. They will not be allowed at the bar and will not be allowed to buy or consume alcohol. Only persons aged 18 or over are allowed to buy and consume alcohol in pubs.