Recent legal wranglings (the dipshits jailed Dr Evil in Wolverhampton despite fully signed consent forms) have made a lot of the body mod community in the UK a bit more…twitchy about taking on work. So it’s really unlikely you’ll find a reputable place to implant anyone under 18. Even where I got mine done (the guy has an implant himself) asked me to keep it quiet and not film it just to be safe, and I’m in my 30s.
You might get lucky and find someone willing to do it on the snide.