If you are under 25, if you are spending over £72 on your train ticket, it would be cheaper to get a Young persons rail card (1/3 off and it costs £24).
If you book a few days ahead, you can usually get it quite a bit cheaper. You can book and pay for it online then when you go to train station, just give them the code to get your tickets (booking at a train company website like first great western will not add any booking fee and you can book train tickets for any company from any one (booking at somewhere like thetrainline will cost more)).