If you are ever planning to travel by rail in the UK, there are two invaluable
web sites. The first railtrack.co.uk will show you timetables for
the entire country; simply enter your starting point, destination and
preferred timings and it will come up with the options. You can ask for
earlier and later journeys. However, this site does not show prices, so
for this you need to go to: thetrainline.com

Here in the UK, if you book your train fare one week, two weeks and further,
in advance, you can achieve substantial savings. Even buying a ticket
to pick up the next day at the station can make a big difference in price.

The two rail journeys where buying tickets in advance makes no difference
is the Heathrow Express, the £12, 15 minute journey from London
Paddington railway station to London Heathrow airport, and the Gatwick
Express costing £11, and taking 30 minutes from London’s Victoria
railway station to Gatwick.