Only thing is I'd make sure the friendlies are affiliated by the county FA. Else if anything goes wrong, the referee isn't 'covered.'
Hes young so at youth should be OK, but I steer clear of 'friendlies' as at open age, they tend to be anything but.
Good luck, starting at a good age and making...
I see all the requests from Sussex FA for these kind of things - seems to be between £25-£40, including food and drink all day.
Sounds like a nightmare so I never bother, but probably reasonable experience for a lad.