I went to NCT classes because my hospital only offered a one day antental course and then another half-day for breastfeeding, and my GP doesn't run postnatal groups. I was sceptical, as was my husband, but we both found them very informative and useful, as well as fun actually.
You really can't make a judgment as to whether the classes will drive you mad, as someone did below, without knowing what such classes cover! Our NCT leader gave us a list of topics she could cover and asked us as a group to separate them into categories re which topics we definitely wanted to cover, which we would like to cover if we had the time and which we didn't mind if we didn't cover. This meant that we set the agenda; very useful. MY NCT leader was very into natural childbirth and, to be honest, didn't have much of a sense of humour. However, she knew her stuff, was very informative and did cover at length C-Sections and intervention, which was just as well as 4 out of 7 of us - including me - had emergency C-Sections. I was much more prepared after the NCT classes than the hospital one, which hardly covered C-Sections. My baby ended up in intensive care and SCBU; my NCT class had covered this but the hopsital one didn't, and I was very glad that I knew a bit about it and what such experience could involve and had covered it in my birth plan (based on the sample one my NCT leader gave us).
My classes were £130 for six two-and-a-half hour sessions and I thought that was good value. The other people in my class were fantastic and four months on, I still meet up with the other mothers every week.
How good NCT classes are depends on the teacher, so it might be worth seeing if you can find someone who had the same teacher you might be going to and sounding them out.
Having said the above, I do think in your case that it is a lot of money for two days. I deliberately didn't go on a two day course in my own area and found out about a longer class in a neighbouring NCT area. My advice to you - if you haven't already done so - is to consider classes in another area. They might well be cheaper for a start. I live in SE London myself, and £200 is a lot more than any of the classes I found out about, including the two day course. There is a great deal of info to absorb and I'm not sure how well one can do that in two days. With a longer course you had time to digest things and return to a topic if need be, plus you are more likely to bond if seeing people on a weekly basis. If other groups are available to you and £200 is a stretch financially, then I would not do the two-daycourse and just read lots of books. But I heartily recommend the NCT classes to other people.