@MadCatLady great glad you have a good boss + employer - I think this is the key differential regardless of our individual support needs
TBH my experience so far has been a bit mixed - but I would say keeping a paper trail of what was said and done is something anyone needs to keep. As time just ticks by, and I suspect many a time things turn sour.
So reasonable adjustments in law sound great but the reality is you're pretty much on your own - and may come down to how hard you wish to push
HR may send you on a Occupational Health assessment - but reality that is fairly quick "chat" that is obviously done for the companies benefit (to see if you'rrre likely to be covered by the equalities act and can you do your current job), well that's HR for you. Thereafter my experience is, that box is ticked, and the detail (which we love ) is lacking and in its place is ambiguity (possibly intentionally) so you never know what's informal and what's formally agreed, and their NT understanding differs for what you thought you need.
Sorry if I sound slightly negative about Reasonable Adjustments