Hiya, it all depends on the church and the vicar. I've had both my children christened in different churches and haven't had to attend church before hand (but i did go once so i knew what the church looked like).
My cousin lives in a different area to us and has got to attend church for 3 months before!
So i'd ring your local church to find out. A christening is free. We had to share my sons christening with two other families but for my daughter it was just us.
Also i'm pretty sure that the godparents have to have been christened and they do like at least one to be confirmed, although none of our childrens god parents are.
Usually its 2 men and a woman for a boy and 2 women and a man for a girl. My 2 have each got 4 godparents but i did have to ask.