I am not in the uk but had a aimilar situation with a long wait for a first appointment. The subsequent appointments were a little bit stretched out because of matching my diary with the gaps still available in the practitioners’ diaries, and after that phase, when we had decided on a treatment plan (I am seeing a therapist and, since november, a coach), I could book six appointments in one go. Round about appointment 4 or 5 of the block, I check if another block of six is a good idea and we discuss whether or not the frequency should change. Then I book those before the last appointment arrives, as I know from my experience last year that I would otherwise land in that zone of shifting sand where it’s hard to line up diaries.
I also managed to get the appointments to settle down into usually being the same day of the week each time, and roughly the same time of day. This helps me a lot, as I can plan around them better. In the beginning my whole day was a washout if I had had therapy in the morning. Now that has calmed down, but I try to keep that afternoon free every week for my planning.
That doesn’t always actually work
Basically, being diagnosed as an adult has been like a project in its own right. I made a decision to allow that to take time, literally one day a week, on average. I am already reaping a lot of benefits, and am far more effective than I used to be. So even though working on improving my behaviour patterns etc is taking up a lot of hours each week, my overall achievement each week is way more than it was a year ago.
My advice on your specific question is to phone the admin person who arranges appointments and ask how that works there.
Good luck with it all! It was an emotional rollercoaster and cost me a lot of energy in the beginning, and I was very uncertain about whether I would regret getting this label etc etc. But now I am really glad I am getting the support I am getting and that things are changing for the better.