I'm sure I've read somewhere before that you have to be at least 18 to enter a candidate for an examination - can anyone confirm this? It's just I've started teaching but I'm still 16, so who would be the best person to enter my candidates for me?

For what? to enter pupil into exam i don't know.

But to take the exam i think you can be any age.

To enter a student into an exam, I'm pretty sure you have to be 18, but to enter yourself, you can be 16 and still pass.
Maybe you could ask the student's parents to enter your student?

You have to be 18 to enter a pupil or yourself (although there must be a different system for diplomas as one has to enter oneself and can do it before 18...) some people have suggested that they have got their mums to enter their pupils for exams if they are not old enough themselves, or your own teacher may be willing to enter your pupils (depending on how good they are!). I think that the AB will write anything that you want them to in the entered by section of the certificate (you can tell them what to write in there separately to the applicants name) so you might even be able to get them to put on your name. You can certainly ask for the presented for examination by bit to be left off the certificate if you prefer. One final suggestion (although this is most probably useless to you) if your pupils are adults they can enter themselves.