We're only provided with one NHS class, which I can book when I am 28 weeks, but if yours says from 20 weeks, I'm sure 22 weeks won't be too early.
I'm definately going to go along to it and will be taking my husband, it'll be October when I will be able to go along.
My friend went to her local NHS class (and took her husband, I believe most women did), which is under a different PCT to me and she said that the class was a bit rubbish really. She said that they showed a dated video and the whole time the midwife said 'we don't do it like that anymore. Ignore that bit'. It was however very comical as a result.
I've managed to get on a NCT class, I'm lucky as it's held 10 mins from where I live - there are lots of yummy mummies around here so luckily a big demand for NCT classes. I'm a bit apprehensive about them though, scared that they will be dead competitive and snotty - fingers crossed I get a good group.
Not sure whether I have helped or not? xx