If you satisfy the medical requirements for a normal UK driving licence you should be fine. You will not be able to fly if you are:
More than 103 kg (~16 stone) fully clothed;
Under 13 years old;
Take insulin regularly for the control of diabetes;
Subject to sudden disabling health attacks such as epilepsy.
If you have a disability that impairs your movement we recommend contacting the office before booking a trial flight.