Then you need to be having a word with your manager as well.
the idea of the equality act is to make things equal -
if you didn’t have MS you wouldn’t be needing to take time off for additional appts or treatments.
therefore under the equality act reasonable adjustments must be made to ensure staff with disabilities are not disadvantaged when taking time for appts or treatments or sickness related to their disability.
by telling you you must take a/l or toil for these appts your manager is disadvantaging you because you are having to use these for appts that a non disabled person wouldn’t need to.
to take it as unpaid is the same principle - you’re colleagues wouldn’t need too lose salary due to disabilities so you shouldn’t but unfortunately- there’s no automatic right under law for it to it to be paid - some employers will allow it to be recorded as sick leave - others have disability leave policies to distinguish between the two which are paid /partial paid or unpaid
—others may just have it unpaid authorised absence - but that would be leaving them open to discrimination claims
if that’s the case that’s it’s unpaid and you chose to take as a/l or toil that’s your choice but it’s pretty shitty to be forced into that position so again - most trusts will have a paid disability leave policy. You may need adjustments in place to recognise this but again this should be automatically considered by your manager.
shift swaps - yes at a push if you are able (ie it isn’t going to cause detriment to health eg if an epileptic nurse was told to have the time off for a neurology appt was only possible if she swapped her allocated day shift for a night shift would be unacceptable
so no shift swaps aren’t enforceable either
in short - the correct and equitable way to record the time is for the treatment itself - disability leave. Post treatment when you are too unwell to work - sick leave - get a fit note.
If you have a good doctor will record first day of not fit to work as the first day of treatment though - it’s sick leave ☺️