Two week trip England/Scotland

Hi!
I plan an England/Scotland trip in the last September weeks. First going from Cologne (Germany) to Calais (France), then by ferry to Dover. Then visit London for a day and travel through England and Scotland to Edinburgh. Finally back from there to Cologne by cheap flight. That's the rough plan. :rolleyes:
I'll have to travel on low budget. Maybe Megabus and bed'n'breakfast/hostels or hitchhiking and wild camping. I'd prefer the latter, but honestly I don't know if I'll have the balls to do so. I'm a noob when it comes to travelling. :oops:
Anyway. Do you know of any places I should visit on my way? Some cool sites, maybe even festivals or alike? Any places I should avoid travelling with a backpack and low budget? Any tips? Thanks in advance! :)