The fourth month is the problem
Illustration, not a forecast: £2,000 a month of essentials needs £6,000 for three months, £12,000 for six and £24,000 for twelve if no other income comes in. The chart assumes zero sick pay, zero savings interest and no insurance payout; real cash need falls if other income continues. A £6,000 pot bridges three months, not a year. That is why the emergency-fund guide and protection solve different parts of the same problem.
The GOV.UK SSP page says eligible employees receive £123.25 a week or 80% of normal weekly earnings, whichever is lower, for up to 28 weeks. That is not a replacement salary; it is also not available to everyone. Eligibility depends on employee status and other conditions. Do not assume a self-employed person receives SSP.