Dont want to travel on overnight train as we want to see the countryside
A coach would take a while, but probably be your cheapest option. National Express have one way tickets from about £30 depending on when you go. Check http://www.nationalexpress.com for details. Not the most comfortable ride you will ever have, but if you aren't going overnight it won't be an issue...these buses are impossible to sleep on, but other than that I haven't had problems. about 8 years ago
Or the train as well - its only about 4 hours and takes you from city centre to city centre. If you book in advance you can get cheap tix, otherwise it can be very pricey. Bus is definitely the cheapest option - but its a long journey....Ive done it once, and never again!
Other cheap airlines to try are easyjet and ryanair. about 8 years ago