Do I need a sickness certificate from the doctor?
You only need a sickness certificate (also known as a sick note, med3 or fit note) if your illness lasts more than seven days.
You can complete a "self certificate" if you are off work for up to seven days. You can download the self certificate form by following the below link;
Do I need a "return to work" note?
No, you do not need a "return to work" note. This is clearly stated on page 8 of the below government guidance;
Obtaining a sickness certificate from hospital..
If you are off work for more than seven days for an illness that has been treated in hospital (including A&E), you should obtain a sickness certificate from the hospital Doctor responsible for your care.