Healthcare professionals' issue fit notes to people to provide evidence of the advice they have given about their fitness for work. This might be to advise changes are required to allow you to work, or simply to advise you currently cannot work.
If you are off work for 7 days or less, you do not need to give your employer a fit note or other proof of sickness from a healthcare professional. When you return to work, your employer can ask you to confirm you've been off sick. This is called ‘self-certification’. Your employer will confirm how you should do this. You may need to fill in a form or send details by email.