For your first week of sickness you do not need to see a doctor for a sick note. this can be obtained from your employer and is called an SC2. If your employer insists on a doctors' note for the first seven days there will be a charge.
Evidence that you are sick
If you are sick for more than seven days, your employer can ask you to give them some form of medical evidence to support payment of SSP (statutory sick pay).
It is up to your employer to decide whether you are incapable of work. A medical certificate, now called a 'Statement of Fitness for Work' (see below) from your doctor is strong evidence that you are sick and would normally be accepted, unless there is evidence to prove otherwise.
You could also provide evidence from someone who is not a medical practitioner, e.g. a dentist. Your employer will decide whether or not this evidence is acceptable. If your employer has any doubts, they may still ask for a medical certificate from your GP.
Statement of Fitness for Work - Fit Note
The 'fit note' was introduced on 6th April 2010. With your employer's support, the note will help you return to work sooner by providing more information about the effects of your illness or injury. For more information go to www.direct.gov.uk.