Hi Rob,
There's a number of Railcards that can offer discounts, you can find more about the different types at the site below
http://www.railcard.co.uk/ Such as the 16-25, family & friends railcard, there's also the disabled person and senior citizen cards, all offer discounts on fares.
There's also the option of split ticketing, which you buy for the same train but have 2 tickets to cover the journey, you can save a lot of cash doing this. There's more info about split ticketing and how to get other cheaper fares on the following site
http://www.moneysavingexpert.com/tra...-train-tickets
Hope this helps Rob.