Getting around the UK is very easy using Public Transport.
Students travel around the country all the time - going to Uni and back home for the weekend.
Friends going to weddings and folks going to London.
London - like big Cities in the US - is a Traffic Nightmare !
Fortunately the UK is about the same size as a US State. Maybe Florida ?
So its only a few hours by road. Trains are much faster - but more expensive,
You're choice. So... look at
http://www.nationalexpress.com/home.aspx
They're really nice coaches / bus links that criss cross the UK. Reliable. Affordable.
And if you're under 26 you can get a Young Persons Travel Card (Students do) for £10 and that gets you another 33% off costs. Plus you get to see our Country out the Window !
And Megabus will get you around too - maybe into Europe if you want.