It'd be good to get along to some NHS ones if you can...if you're due in January you've got loads of time!
I think we attended 2 out of 5 classes at our local NHS hospital, due to work commitments.
It was interesting I guess but nothing I couldn't have found out on here.
The one thing I remember is the midwife saying that if you wanted an epidural you had to just ask the midwife and a doctor would come to do it quite soon after 
Also, reassuring us that episiotomies were "not that bad, just a small cut'...as I thought about one of my close friends who needed surgery to sort her out a few months after having her baby.
I don't think the NHS classes helped create realistic expectations to be honest!
We didn't go for NCT- far too expensive and we wouldn't have qualified for any income discounts.
It would have been great to have a ready made group of friends...but I'd heard mixed accounts of NCT from friends & acquaintances.
One loved it and they are all still in touch a couple years later, another friend said the group did not gel at all!
If you've got the spare cash, go for it.