what is the transportation like out of Chesham?
If I wanted to get a train or a coach to other parts of the UK, what are the main hubs? Oxford, even London?
More specifically, any ideas how to get to Bristol?

You can easily get the train into London from Chesham, takes under an hour and I think two trains an hour. You can get a bus to Berkhamsted or Hemel and then trains from there to places like Milton Keynes or London. Also there is a bus from Chesham to Heathrow. Hope that helps.