To obtain your provisional category C licence you need to undertake a driver medical. A renewal HGV/Bus medical is required at 45 and subsequently every 5 years until it becomes an annual requirement from 65. There can be exceptions to this rule though and you should always check the date in column 11 on the back of your driving licence.
The doctor will complete your full D4 medical during the examination. Your medical consists of an eyesight test using a snellen chart, blood pressure checks to ensure your BP meets DVLA criteria and a questionnaire regarding your medical history.
Your medical assessment will also include checks for other standards that need to be met by drivers of group 2 vehicles. You will be asked questions regarding a range of issues such as epilepsy, seizures, insulin treated diabetes, and many other forms of medical condition, in order to ascertain if you meet the conditions not to be refused for a group 2 licence.
The doctor will complete your D4 form based on the answers you provide relating to your medical history, medications and the findings of your examination. The whole process of carrying out a HGV medical should usually take around 30 minutes but this does depend on your health and medical history.