You'd get away with the NHS ones.
Our NCT classes were a bit of a waste of time, the woman who ran them was lovely but very airy-fairy, so we didn't actually get as far as second stage, and I was clueless when it came to giving birth.
Maybe it was just our teacher at fault rather than the NCT itself, but we were given the impression that there is an "NCT Way" to give birth and feed a baby, and everything else is wrong. It was very idealistic, which can lead to people feeling bad if they don't manage to attain the "ideal" birth.
There was almost no information available about any kind of assisted birth - c-sections weren't covered, and the only references to such things as induction, forceps or ventouse deliveries were very negative - plenty of horror stories but nothing positive. So we all felt under huge pressure to have the "perfect" birth - no intervention, no assisted delivery, and even pain relief was frowned upon. I ended up having an emergency c-section and when we all met up with the leaders after we'd had our babies, I felt that I was somehow pitied for not having a "proper" birth.
Their stance is very pro-breast feeding as well - as am I - but with my first I wanted to understand as much as possible about feeding and to be prepared for every eventuality, but when I asked questions about formula feeding I was treated very frostily and although there was plenty of information about breast feeding, there was no information or support for anyone who chose to formula feed. I was simply told that every woman can breast feed, and it's laziness that makes them want to do otherwise. Which made the four members of our group who couldn't/didn't want to breast feed feel really good.
We made some friends from the NCT classes, and that was their biggest benefit to us. But it was a lot of money to pay out for the privilege!