I second what other people have said about driving in Scotland - it will take you twice as long to get from Central Belt to North Scotland than it will take to get to Scotland from England. And if you are not used to driving on these kinds of roads, it will be exhausting as it takes quite a bit of concentration. And if the weather is poor it is significantly worse.
There is so much to be seen around the lower regions of Scotland which would serve as a great introduction without overwhelming yourself with an itinerary which is a stretch. I think you'd be disappointed if you tried to do the far north on 5 days.
The drive up to Scotland on the A1 has spectacular views - it's not a road to be rushed though. Visit Coldingham & St.Abbs and try out a boat trip/marine tour to see a variety of marine life. Follow the coast around and stop at North Berwick for a quaint seaside town and visit the beach at Yellowcraigs - the sand is plentiful, soft and neverending. Greywalls in Gullane or Duck's Inn Aberlady has lovely food.
My favourite part of Scotland is Perthshire, it's very lush and green. You could head up to Callendar and cross over past Loch Tay to Pitlochry and then north to Aviemore - the scenery here is gorgeous. Visit the top of the Cairngorms (on the Funicular railway) stopping to vist (or walk around) Loch Morlich Beach. Then if you want to see mountains head back down Grantown on Spey, Ballater, Balmoral, Braemar and Glenshee. If you've got time before home, a visit to my favourite Castle (Stirling) before home.
Now being honest - that is also probably too much to do in 5 days, I'd consider missing out Aviemore or at the least only use the A9 and miss out Glenshee because those rural roads are slow going, especially given the altitude covered as well as the sheer distance.
You could also head up M6 and cross over the Scenic A7 route or leave at Moffat and head over to Selkirk (lovely scenery!). Melrose, Jedburgh & Kelso, and head right over to St. Abbs/Coldingham on the East Coast.
Some ideas here, hopefully more food for thought.