Can I take sick pay directly after my maternity leave?
If you are in the UK, yes you can, provided that you meet the normal requirements for taking sick leave, such as having a valid doctor’s certificate (which I assume you do as kidney failure sounds fairly serious). Read your employment contract or staff handbook to find out what pay you’re entitled to. Some companies will offer full pay, others offer full pay for a limited time and then you revert to SSP, and others offer SSP only. It should also tell you if there is a limit on the amount of time that they will keep your job open for if you’re on long-term sick leave.