If you are off work for less than seven days, you are responsible for your own self-certification on form SC1 (available from reception or any post office).
After seven days a doctor's certificate (Form Med3) is required. You may not need an appointment if the doctor is already aware of your condition. Telephone the surgery for advice if in doubt. Employers are legally bound to accept self certificates. Some, however, still insist on a doctor’s certificate during the first seven days of absence, in which case a private certificate will be issued and a fee will be charged. Your employer may reimburse you.
Please note that Med3 certificates cannot be issued in advance, but they can be back-dated.