Anytime (no restriction)
Single: £54.50
Return: £109.00
Off-Peak* (Not valid before 0840 or between 1640 and 1830 Mon-Fri).
Single: £39.00
Return: £40.00
*THIS TICKET IS VALID AT ANYTIME, WITH NO RESTRICTION ON WEEKENDS/BANK HOLIDAYS.
You can buy all of these tickets on the day, with no need to book in advance. If you can book in Advance, (usually a few weeks before travel), you may be able to get tickets priced from £7.50-£30.00 Single. These are only valid on a specific train, on a specific date. The Off-Peak Return ticket is only £40.00 so you're probably best getting that, (£20 each way seems reasonable).