It is available from Disability Rights U.K. for the sum of £4.50 – if you are disabled then you do not need to pay VAT. They only sell to anyone who needs to use a toilet as part of their disability or health condition. I would argue all day that CKD & dialysis patients fit into that definition very easily.
The key itself is mainly for using a disabled toilet. There are 100s dotted around the UK (you can buy a book showing all the locations but I didn't see the point). Very useful given the fact that (a) pooing is important, and (b) if your luckily enough to still be seeing on dialysis then it's important to keep doing it!
However I found out only yesterday that the key does something else – using the key I could use the lift as a station.
It was brilliant! And something I haven't seen before! So it is something I recommend you get. Maybe pop it on a birthday list or Christmas list so you don't have to pay any money – #winning