You only need a doctor’s note if you are unable to work and are ill for longer than seven calendar days. Your employer may ask for a SC2 self-certificate form for shorter periods of illness. These are available from reception or to download.
More information regarding fit notes can be found here
Please be aware that if you are off work due to a hospital procedure then the hospital consultant will need to provide you with a fit note for the duration of your recovery.
Sick/Fit note online form