Originally Posted by
FlyingJesus
Technically there's no legal age of piercing in the UK that I know of, but most piercing parlours will ask that you're 16 (or 18 for genital piercings, for obvious reasons). However, under this age you can get pierced with parental consent.
If you're very young or if you have a lot of growing to do the piercer may recommend that you don't go for it just yet, and if they do this then take the advice because if they're refusing your money because they think it's not a good idea, then they must be right about it. Do not go to a different place and get it done anyway, you'll come to regret it.
Guessing you're still talking about lip, and labret is the basic lip piercing (centre, bottom lip) not a jewellery style. Ring or bar won't make much difference, except that a ring can obviously get caught much easier and so is less likely to get agitated (and therefore might have a quicker healing time). Healing time generally depends on the person, but it won't be a week or two if that's what you're hoping, and if your school has a policy against lip piercings, I'd wait until you finish school rather than risk having it close up/get agitated from changing jewellery too soon. As for having a retainer for it, ask your piercer if it's possible to be pierced and have the retainer straight away if you want that, just in case the above situation occurs.
Of course, I'm not a piercer myself, so I would still advise that you ask your local piercer these questions.