Yes, you can sue anyone under the age of 18, yet they won't be accountable for the debts till they are over 18.
MoneyClaim Online is a Online Small Claims court, use it fairly often in my line of work, especially in close proximity to Carillion going bust and almost taking other companies with it.
I digress, start a moneyclaim online, it's like £50, name the child/minor as the defendant as follows "<Childs_Name>, a child by <Parents_Name> their litigation friend"
Litigation Friend basically means, as a child can't make decisions themselves, their parent shall,
https://www.gov.uk/litigation-friend
As part of MoneyClaim online, you may enter mediation, where you can agree a sum, if not it goes to a hearing.
Yeah it's a tiny amount of effort, but you can probably get it all logged with a witness statement and photos of the damage and a quote for repair in about 30 minutes.
He sounds like scum so I'd do it personally.