Anyone can make an appointment to see a doctor or nurse, no matter how old they are.
You can book an appointment at your GP surgery by calling them up. You will be able to find the number to call by searching the name of your GP surgery. Some GP surgeries allow you to contact your GP for advice by filling in an online form and they will reply back by phone or email.
The receptionist will ask you who the appointment is for and why. This is to make sure that you see the right person at the right time.
If it’s something personal then you don’t have to tell them why. Just say it’s for something personal. You can also ask to see a male or female doctor or nurse if this would make you feel more comfortable.