I found hypnobirthing almost completely useless in my first labour (24hrs, agonising back to back labour, failure to progress, ended in forceps). I think the fact that I went into the labour believing my body could do it, and believing I could do without pain relief, left me completely unprepared for what was to come and also led to my feeling like a failure afterwards.
However, my second labour (no hypnobirthing!) was entirely straightforward and was quite a fantastic experience. Drug-free, quick and amazing waterbirth. I'd gone in with no pre-formed ideas as to what I wanted from labour, but everything just worked as it should and I pushed DD out no problem. I tore badly (second degree tear) but hardly felt it!
If I'd had the easy birth first time, I have no doubt I'd have put it down to the hypnobirthing. But in reality it's just luck of the draw and largely down to baby's position, IME.
Talk of pain threshold is also bollocks, IMO, as labours can be so different. My second labour was extremely painful but I was entirely able to cope and feel I had some control. It felt nothing like my first, during which I'd have happily shot myself in the head, given the chance.
If I were you I'd just try and relax (I know, easier said than done) and put no pressure on yourself. Chances are, you'll have a straightforward birth - but if you don't, that's what pain relief and c sections are there for. The emphasis on "natural" birth by the likes of the NCT does people no favours, I think, and can create a lot of unnecessary pressure. Best of luck, OP.