Well originally I just had one appointment with them a year and it all worked out quite well.
Recently I've been on a quest to get my estrogen up and I was switched to Sandrena which didn't work out for me, so then I needed to request to be switched off it and to patches and gel. Since I'd had a proper appointment about 3 months before this, I just had a 10min phone consult with my Newson doctor. That was £100. Then I had to pay another £100 to reverse that(!) and get off Sandrena and back onto gel along with patches.
Which is all to say, it depends how much you'll need to change dosages or products. Once you are stable on something it should be fine.
And it has all been cheaper than the ridiculous private thyroid care I've also had to pay for over the last year, trialling thyroid meds for symptoms which were actually low estrogen. I think it's been about £1K just for the thyroid stuff because it involves bloods every 6 weeks and expensive T3 meds and more private doctors' appointments than meno stuff.
I'm weaning off thyroid meds now. I began at 50mcg T4 and 45mcg T3 - and today I'm on 25mcg T4 and 30mcg T3. It will be another couple of weeks before I'm completely off. I'm doing okay so far.