It is not necessary to have a Doctor’s certificate until you have been absent continuously from work for seven days including weekends. After three days you must obtain a self-certificate (SC2) from your employer. If your employer insists on a private certificate for an illness of less than seven days duration then the Doctor will charge a fee of £15. If your illness continues for more than seven days then under the NHS your GP can issue an official statement (Med3) “fit to work certificate” to confirm your illness.
You can download the SC2 form here: SC2 Form
The ‘Fit Note’
The ‘fit note’ replaced the doctor’s sick note on 6 April 2010. With your employer’s support, the note may help you return to work sooner by providing more information about the effects of your illness or injury.
Information about the fit note (employment section)