Tell your manager before 9:30am on the first day you are off. You can self-certify for up to 7 calendar days and need a fit note from day 8. Once you are through probation you receive full pay for up to 10 working days of certified sickness in any rolling 12 months. After that, or if you do not qualify yet, Statutory Sick Pay is paid at the statutory rate and for the statutory duration if you meet the conditions. See Sickness absence (UK).
UK and Kenya handbook sections are authorised demonstration content pending HR approval · Not legal advice.