Hello, sorry but from my experience I do not have much good news for you
My post may be a bit depressing for you as I worked for the NHS and actually did have to give up work because my SLE made it impossible to keep working.
In the end what happened to me did become the most suitable option and in the long term it has helped me become more stable with my SLE symptoms and in overall better health. (I can now rest when needed, pace my activities, and avoid work stress etc)
However, it made me very ill as I went through the process. I almost got to the stage that my house would be repossessed unless I got some money soon. My experience included getting "Dismissed due to ill-health". I had to go through a lengthy appeal before I was finally granted "ill-health retirement" pension money. I now have to survive on a much reduced income, and I have had to accept that because I have Lupus I'm incapable of working (probably for rest of my life/until a cure for SLE fatigue is found).
The whole process will be stressful and can actually make SLE flare up through the stress. You will also have to take a really good honest look at the assessment of how ill you really are and what you realistically can expect to be able to do work-wise. This includes your current job but also includes the "foreseeable future" prospects of if you are capable of doing any type of work/will ever be able to.
I would advise getting all the help and advise you can including info from the CAB, from social security, from a union rep, re all the options/financial implications of these options.
Also try to get the advise and honest opinion from your GP & consultant re how much they would support you trying to stay in work/ how much they agree that your health makes it impossible for you to work, as you will need letters of support for your case regardless of which route you end up on.
It will also depend on your personal circumstances - eg if you are very young & only have a few years service in the NHS any "ill-health retirement" is probably going to be very difficult to get & not worth much money (but even so it may be better than getting "dismissed due to ill-health"!).
Also have at least one other person with you to record/take notes at any meeting you have in future as comments such as the "diet coke" one are not acceptable
My experience may give you an idea of what you might expect, sorry it's not more upbeat

The hospital I worked at had a sickness policy they had to follow so after a certain number of days off everything got triggered, and things got more & more serious as time went on and the amount of sick leave I had increased.
Initially it started with health reviews with my manager, then occupational health involvement, letters from my GP etc.
This then progressed to attempts to accommodate me under the terms of the DDA - (I tried all sorts eg cut my hours, gave up some of my role for less stressful/demanding tasks, had a couple of attempts to take a big break from work (2months) to try and improve/give new medication chance to work etc before returning to work, and I tried gradual rehabilitation when returning after long absences).
Finally my sick pay (SSP) was coming to the end, the sickness policy procedures were reaching the final disciplinary stages stages, my health/sickness absence was still very poor, and it was becoming obvious that my SLE treatment was not significantly improving my health, ( by that time I'd been ill for over a year and off work permanently for the last 4 months) so my union, my manager, GP, & self all agreed to try for "ill-health retirement".
However even though going down the "ill-health route was deemed correct by everyone, initially my application was declined (they accepted my disability prevented me from doing my job but were not satisfied that I would not improve /be incapable of working for the rest of my working life)
At the same time I got this news SSP totally ended so my only money was from the social security (they don't fully pay your mortgage) and to top it all I got "dismissed on the grounds of ill-health" from my NHS job ( yes they can do all that & still be in legal rights under DDA)
As my SSP ran out Social Security benefits (what used to be Incapacity benefit) via the job centre a kicked in - these benefits (now called ESA) depend upon having enough national insurance contributions and also on your health & ability to work. (It would take too long to go into here but if you end up on ESA instead of your current wage you will have to prove that you are not well enough to work etc and it's not a large amount of money/does not fully pay towards mortgage costs)
Also I think you have to have worked for a certain number of years before you are entitled to ill-health retirement ( & the retirement pension money) & how much pension money you would get if successful would depend on your average wages & how many years service you have had.
Beware of my experience I loved my job & was worried about losing my wage, home etc so really struggled to keep in work -I kept trying to get my GP to sign me back on as fit to work/ say I may improve as the Plaquenil got time to work, and generally tried to get my Dr's to support me staying in work/say how I was capable of working. However in the end this went against me in the pension makers initial decision and in order to appeal the decision I had to then get all my Dr's to say how bad I was and incapable of doing any kind of work !
Not sure if there is any way out of this "catch 22" situation as at first everyone is trying to say you may be well enough to work if given sufficient support.
Personnel dept, occ health, managers etc must try to make adjustments that allow you to work despite having a disability (if they don't then you have a case under the DDA). In trying to accommodate you under the DDA they have to look at all options re your health & your job and they will do this before they can recommend that you apply for ill-health retirement.
However if you end up on the "ill-health retirement route" then you have to prove that you are not fit to work, including working in any job/ your ability to work for rest of your life as the pension decision makers can say (as they did to me at first) - we accept that you have SLE & can't work but we don't have enough evidence of how permanent this will be/that it will prevent you from doing any type of work or ever working for as long as the pension money would be paid if granted (ie until I'm 60)