There is no legal minimum age for plastic surgery in the UK. For purely cosmetic procedures most clinics and surgeons will require the patient to be at least eighteen years of age. It is now unknown of for plastic surgery to be carried out on patients under eighteen.
Usually when those under the age of 18 have plastic surgery it is for medical reasons only. The candidate must be referred by a GP or medical specialist and only certain types of plastic surgery are permitted. For example, it is very rare for a surgeon to carry out breast augmentation on someone who is younger than 18.