You do not normally need a sickness certificate for the first seven days of illness.
The Statutory Sick Pay Regulations state that employers are required to accept self-certification notes (filled in by you) for the first seven days of illness. All employers must comply with these regulations. These forms are available from your employers who should be aware of these rules.
You only need a doctor’s certificate during the first seven days of illness if you wish to claim benefits other than Statutory Sick Pay: For example, benefits under the private insurance scheme, or to take your pre-booked holiday as sick leave instead. In these circumstances we make a charge of £13.00 for a private sickness certificate.
To continue to claim Statutory Sick Pay after the first week of illness you will need a doctor’s certificate, which will be provided free of charge.