I have heard of some people getting very cheap tickets from websites where you can book an advance trip quite cheaply. any ideas? I need to travel to London for a day trip in a couple of weeks. Thanks
There are no fares available from Megatrain, Trainline or any other website that aren't available directly from the train operating companies. (In some cases you actually save money by booking directly with the train operators because you avoid booking fees). To check the availability of advance purchase fares for you journey, enter the relevant information here http://www.nationalrail.co.uk/
click 'Search' and then click 'Check fares'.