Can I buy a train ticket online in the UK using a UK credit card

I need to buy two tickets for a soft sleeper to travel from Wanzhou to Beijing on 16th April 2014 but I would like to buy them online before I leave the UK. Is this possible and can I pick them up at the railway station in Wanzhou a couple of days before I am due to travel, presenting my passport as identification? Also can I use a UK credit card to pay for the tickets?
Thank you