Comment by Fluorescence

The other option is "Right To Choose" through the NHS - you ask for a referral by your GP to a private ADHD specialist.

The NHS ADHD waiting list in my region was over 6 years but using RTC, I was diagnosed in around 6 months with no extra cost and prescriptions costing the NHS standard. Places like ADHD360 and PsychiatryUK focus on high throughput / low cost so the amount of time and qualifications of the practitioners won't match hand-picking a private psychologist but you can't argue with the cost.

https://psychiatry-uk.com/right-to-choose/