So mine was also quite similar! Over 12 months trying and issues with periods most of my life but pushed away and gaslighted for over 10 years but finally said enoughs enough, had TV ultrasound and all bloods, partner semen analysis then doc had all things required to put through the fertility referral.
In the mean time after 2 months waiting and unbearable periods I also used my private healthcare and had MRI and lap, removed stage 4 endo in several places, discovered a tube was completely blocked and left ovary not working at all with no follicle. Mentally I was really struggling and called the Stevenage Lister fertility/gyno department to see what was going on, how much longer to wait etc and just broke down completely. I got the next appointment they had, for 4 months time (they are incredibly backlogged).
Docs are useless in what they need to do in this interim period and have no idea what goes on tbh, so when the NHS fertility appt does come through they will essentially send you home and book you in again (could be for in another 3 months!) if you don't have a second semen sample (from within last 2 months) and if your results are showing no reason for infertility they will also want to see urology investigation from the male side.
If you can have these things on that first appointment you get your funding very very quick and pick your clinic and off you go.
Otherwise after that first NHS fertility appointment it can be a lot of waiting for appointments and back and forth jumping hoops. Luckily the nurse at Lister gave us all the tips so could have all ducks in a line before hand for a speedy process.
There is only 1 chance in Herts which is sad, and to be honest the fertility clinic choices really aren't the best. Being closer to London than myself though hopefully you will have a few other options open to you!
Hope that makes sense, feel free to fire away with any other questions!