The doctors will carry out medical examinations, such as insurance and employment medicals, HGVs, taxi drivers, which are not included within the NHS remit.
Appointments for these are to be arranged with the doctor via the receptionists, who will advise you of the fee, as recommended by the British Medical Association.
There are also fees for private medical reports and certificates. For example:
Private sick note (less than seven days)
Private prescription (travel)
Holiday cancellation certificate/letter
Fitness to travel certificate
Elderly drivers certificate