private diagnosis - costing and legitimacy

• I am finding work harder and harder without accomodations (mandatory 'return to office ' mandates of X days a week keep changing and stressing me out), and I am in the fortunate place that I am paid well enough to afford a private diagnosis (as I hear the waiting list for NHS is 5 years?!). There are a lot of companies online, it seems the price can vary from £700-£3000...

Obviously the cheapest option would be appealing, but I would also want to make sure any diagnosis is "official" in the eyes of my employer and I guess the NHS. I do have private medical insurance with work,but assume it wouldn't cover something I was potentially born with.

Ideally would want somewhere 1k or under. I would prefer my parents not have to attend in person as they live far from me.

Does anyone have any recommendations please? I am 33F if that matters.