From experience an NHS diagnosis take MONTHS and for some isn't worth the wait, that being said obviously a private diagnosis isn't always an option for everyone since they're hella pricey and not affordable for a lot of ppl (mine was £3k). I felt I had to choose the private route cuz I needed to pattern my life ASAP, being a student at the time also facing exclusions for distractive and "self sabotaging" behaviour, and my assessment was a good six months after exams.

See your GP first and foremost and discuss your symptoms and you should get a referral.