To qualify for SSP you must:
be classed as an employee and have done some work for your employer
have been ill for at least 4 days in a row (including non-working days)
earn at least £123 (before tax) per week (as of April 2023), and
tell your employer you're sick before their specified deadline (or within 7 days if they don't have one)
SSP is only available for a maximum of 28 weeks and cannot be used in conjunction with Statutory Maternity Pay.
For more information, read Sick pay.