Because the nose doesn't stop growing much before the age of 18 years, it is unlikely you could have such surgery until that time. Not sure about the consent side of things. It is normally advised that parents attend consultations with their children up until they are the age of 16 so one would assume from that, that after the age of 16, the patient can sign for him/herself. But please don't hold me to that! And this all relates to NHS treatment. Private treatment may well be different of course.