Doctors and nurses do their best to see you at the time of your appointment. However there will be occasions when they run late because the patients they have seen before you needed more time due to the nature of their illness. On these occasions your understanding will be greatly appreciated and remember some day it may be you that needs that extra time.
If you are more than 10 minutes late you may be asked to rebook in fairness to the patients who have arrived on time. The doctor or nurse may have indicated to reception that you need to rebook, if not the receptionist will always ask if you can be seen.