Try http://www.altontowers.com/parksite.htm
- although it doesn't detail the particular railhead in question, I'm sure if you enquire via the website, they'll be only too pleased to help.
You can definitely pay when you get there, cost �19.50 - �26.00 per adult depending when you go.
On the website they direct you to www.centraltrains.com but there's also a phone number, 0870 000 6060.
The closest station is Stoke-on-Trent - about to be closed for a couple of months while they upgrade the Northern Main Line. Beware - what none of the promo. literature tells you is that Alton Towers is in a small country village and the roads in are always jammed with punters, so drive if you can, and get there early to beat the queues of coaches you will encounter if you leave it too late.