Remember to always book the train tickets in advance. This is the only way to avoid horrendous high rates for UK trains. You can save up to 80% comparing with the rate on the day of the journey. Also you won't have to queue. You can buy train ticket up to 2 hours before departure, but it's much better and cheaper if you book long in advance. The ticket can be easily obtained at the station from the ticket machine, after providing the credit or debit card you used for the purchase.
Please check the rates and availability using theTrainline.com search engine.