(copy+paste from Nat Express website)
Want to discover the UK your way?
National Express brings you Brit Xplorer. That means 1000 destinations to visit and three great passes to choose from - it all adds up to one incredible adventure! If you've just arrived in the UK, or you're heading this way, you'll find the best way to explore the country is with a Brit Xplorer pass.
Travelling with Brit Xplorer will cost you less than going by train, and you won't be stuck with a rigid tour. You choose exactly where you want to go and when - whether it's England, Wales or Scotland!
The three different passes last for three different amounts of time:
Hobo: 7 days for £79
Footloose: 14 days for £139
Rolling Stone 28 days for £219
Awesome deal IMO as I wanted to do a lot of traveling (international student here studying in UK, going home in a few months), wanted to check out places like Edinburgh and Cardiff and Manchester but put off by the high price of traveling.