Oh, wow... we went to one session and just couldn't go back. The religious overtones were just over the top. If we were Christian, maybe the overt Catholic viewpoint would not have been so irritating, lol... honestly, sometimes it was hard not to laugh at some of the corny things being said. The fertility info itself was good, but the curriculum has a conservative bias and a tendency to present anecdotal evidence as fact (its been 2 years or I would give examples).
Perhaps you can find someone locally who can counsel you, either as part of a class or two-on-one. Some midwives are very experienced at NFP and are happy to teach it to others. I wish we'd done that instead.
I do not at all mean this as a flame, I just wanted to offer another viewpoint on these classes. We were told by our Christian birth class teacher that C2C wasn't overtly religious, but my definition of 'overtly religious' is apparently different then hers, and assuredly different then the previous two respondents

It's a shame, because NFP rocks and I think a lot more people would learn and use it if was taught seperate from religion.
XM