There is a great, and very cheap bus service that has quite a few routes around the UK, it's Megabus. This is a very good service, with bright, clean double decker busses with on board toilet. They do express services between various UK cities for dirt cheap, as cheap as a pound for a one way fare, sometimes rising up to as much as 3 pounds closer to the departure date, depending on availability. You can book them online and by telephone and there's a 50p booking fee. Take the email or a text message on your phone to show the driver the booking number. We booked two tickets down to London and one back for a grand total of £7.50. National Express is now matching some of these deals but I don't know how limited their seating is. I find busses a bit cramped but this was no worse than any other bus. Definitely check it out. In London, the bus arrives and departs from the Green Line coach station, right across from the Victoria coach station. Check their website for routes and locations of the bus stops. Quite often the bus may not use the main bus station, but stop outside on the road or it may use a different station than the National Express one. Most routes go to London. Other destinations from your departing point may be limited. There are usually comfort stops as well.