If it was me, I would take a direct flight on Delta from Detroit to Heathrow, then take the train everywhere else. Not only will it be less of a pain, but you will get to see a lot more of Europe along the way instead of just flying over it. But, if you are trying for flights check British Airways, Ryanair or Flybe for Zed fares. I haven't checked to see if we have agreements with them. call the Pass Bureau and good luck