How do I get a sick note?
You do not require a doctor’s sickness certificate for any illness lasting seven days or less. Your employer may however require you to complete a self-certification form (SC2) which is available from your employer or on the HMRC website.
If you are ill for longer than seven days, your employer will most likely want a fit note from your GP. You will need to book an appointment with a GP to request a fit note.