These are sometimes called mitigating circumstances notes, or letters.
Most educational establishments have a sickness absence policy stating that you can self certify for a short period without needing a doctor’s note.
For example, the Sickness Absence Policy for the University of Liverpool states that a self certificate is valid for absences of up to 5 days (with a few exceptions). Most universities will have a similar policy.
If you do need a doctors note for university, this is considered as non-NHS work and therefore there will be a charge. A list of our current charges can be found here.
If you are regsitered with Brownlow Health Central (which includes the Student Health Centre), or Brownlow Health @ Marybone, you can usually make use of the eConsultation facility to request a sick note.