Hello mrsbell -
I had a planned CSection (NHS) last year for severe tokophobia. I think I got mine confirmed somewhere around 22 weeks, but had been given to understand by my MW that I would almost certainly get one (it was still an almighty relief to get it confirmed).
I can only post briefly now, although I have posted in some detail about it on this board before, and will check back later if you want to ask anything specific.
I just want to say - don't assume you will have to 'fight' the NHS - it will be more helpful for you to have HCPs on your side, and supporting you. A referral to a psychiatrist should be a good thing. A very sympathetic consultant MW referred me to a perinatal psychiatrist, who recommended I have a C section, and that was pretty much that. I dealt with a very relaxed and sympathetic consultant. Maybe I just got lucky, but I got the impression I wasn't the first woman in that situation they had dealt with.
I think it helps to be well read about the risks of C section as you can be (and I can't think why anyone wouldn't want to be well informed) - but bear in mind, in your position, if you get a CS it will be because of the serious risk of a bad outcome for your mental health if you are forced to go through a VB against your will, not for any other reason.
I know that's obvious! But people tend to talk about the physical side only of CS's - tbh, if your fear is so strong, as was mine, the emotional and mental health aspect of it comes into play very strongly, and are (or should be) taken into account. Which is just what writerofdreams says, and she's right.
Do ask if there's anything you want to know, and I will try to help.