Loch Lomond in October will be a huge treat and adventure for a 6 year old. You have all of the west of Scotland up to Oban available to you and central Scotland north of Perth. So much to see and do and the Heather and autumn colours will be at their height. It’s possible to spend a whole day just playing and relaxing on one of the many small beaches around the loch, paddling in the water, starting to learn about geology from the stones and rocks and maybe lighting a small fire later in the day.
Queen Elizabeth Forest Park is not too far away, with trails, bike riding, pony trekking and a hide in the visitor centre to look for red squirrels, roe and red deer and golden eagles. There’s a waterfall trail and a Go Ape site for high wire adventures.
Or head over to Oban and drive over the ‘bridge over the Atlantic’ to Seil or get a ferry to Easdale island where the world stone-skimming championships will just be over and you can teach your son this skill with the special stones from the quarries there. You could take a longer ferry trip to Mull, a most magical island, with abundant wildlife including white-tailed eagles, wonderful beaches and dolphins to see.
Stirling castle and the Wallace monument are worth a visit along with the splendid Bannockburn centre.
If there’s a spot of rain, head to Glasgow to the science centre or transport museum, each needing a full day to enjoy.
On car trips, show your son how to ‘read’ the landscape, where the tree line is, and to watch for wildlife in the hills, around the edges of lochs and in the sky.