I'm appreciative of all the advice! I think the newest plan is to take a train from London to Newcastle. Rent a car there, drive to Chirnside for a couple days, drive to Edinburgh, hang out there for a few days, go to St. Andrew's, go to Inverness, loch ness and all that, and then drive back to Newcastle, return the car and take the train back to London.

But perhaps return the car in Edinburgh and take the train to St. Andrew's and on to Inverness? A lot we just want to play by ear when we get there, but I'd at least like to know what sorts of options we have!