Get a Sick Note/Fit Note
Non-urgent advice: Here Are the Most Effective Ways of Getting a Sick or Fit Note
Online via 'econsult'
Note: You do not need a sick note if you are off work sick for seven days or less.
Only when you are off work sick for more than seven days will you need a medical certificate. The seven days include days that you don't normally work. When you work out how long you've been off sick, you should include weekends and bank holidays.
Note: Medical Certificates can be back-dated where appropriate but not forward-dated.