I have to say, I didn't really get on with the NCT. It seems like they are either made up of "earth mother" types, or very much non-earth mother types, dependent on area. Nothing wrong with either, but there is a problem if you end up with a non-compatible group to you as I did. Its then a bit like your first day at school/uni where you make friends that you really don't like all that much, just to get through the expereince.
Also, our teacher was really out of date, the classes were either at 9.00 in the morning (on a workday!) or 8.00 at night (not great when you're 8 months pregnant), they were scheduled so over half of us actually had a due date before the classes finished, partners were excluded from about half the classes, and they were right out in suburbia where NO buses or trains dare venture. Everyone was super-yummy and drove huge new cars (bit of prejudice creeping in, sorry).
You mention Active Birth-have you considered the Active Birth centre? I know it is in North London but maybe its not too far? Also, if you are at all into active birth etc you might meet people at things like yoga for pregnancy (a lot of teachers also do baby yoga) etc. Yoga really is meant to be helpful-it helped me have a 2 hour labour! (I'm an Earth Mummy type, I'm afraid)
Having said that, you're not in the same area as me, and I do know people from other areas who loved the NCT classes. I'd personally say have a back up way to meet a support network. A particular problem for me was that we didn't at the time have a car, and these people kept arranging to meet in various yummmy and far flown (and expensive) locations so I gradually lost touch.
Sorry-this has turned into an NCT rant. I guess I do think they are basically a dating service for middle class, married (EVERYONE in our class except us) 30 + mummies of one and I didn't fit most of that profile.
I will say that my parentcraft classes were fantastic. I think it is totally dependent on the team of midwifes.
But honestly, if you're just there to learn, not make friends, you can get it all off mumsnet! And I personally don't think relaxation helps much during labour. However, pethadine is excellent.