We are traveling to Edinburgh in August 2010. Flat is already booked. I'm looking at flights and it is a lot cheaper to fly to London than to Edinburgh. What would the cost and hassle be to take a train from London to Edinburgh? How much time does the train ride itself take? I assume that we would have to fly into London and then get a cab to the train station? Is it better to fly into Heathrow or Gatwick if we go this route?