5 day self driving itinerary

First, don't have a rental car for the Edinburgh portion. Do Edinburgh either first or last and rent the car as you leave or drop it off as you return. If you're flying long-haul, take a taxi/tram from the airport into Edinburgh rather than driving while jet-lagged.

Your itinerary involves a lot of driving, so you might want to drop one of your objectives, especially If five days includes your travel in and out.

You could fly into Edinburgh, and spend two nights in Edinburgh, giving you one full day to see the Castle and other stuff.
The next morning, rent a car and drive to Glencoe and spend the night in Glencoe or Fort. William, doing some hikes in the afternoon.
Day four would be a drive up the west side of Loch Ness, stopping at Urquhart Castle, lunch in Inverness, Culloden, Clava Cairns, then drive on to maybe Grantown-on-Spey for the night.
Day five could include driving to St. Andrews in time for poking around the castle and cathedral, and maybe stay nearby or return to Edinburgh, depending on your flight times.

If you can answer these questions, it would be helpful and make it easier for us to answer your question.

• First, are you flying into Edinburgh or coming there from someplace else?
• Once you get there, are you spending 5 or 6 nights in Scotland?
• Are you planning to spend any time in Edinburgh in addition to seeing the castle?
  
• And are you planning to visit St. Andrews as a day trip or stop on the road? Keep in mind that visiting St. Andrews will take you a full day, and the castle will easily take at least a half day or more, depending on how much you want to see.

We will be coming into Edinburgh from London. Thought 5 days and 6 nights possibly. Still working it out. Fly back to London or take the train.

Thought St. Andrew as a day trip and really just one day visiting the castle in Edinburgh and walking around.