And keithj was spot-on to suggest the Cape Wrath Trail as the journey name. There's no signposting, no constructed trail, and not even a fixed route. You just get yourself from Fort William to Cape Wrath however you like, by connecting your choice of glens (valleys) and bealachs (passes).
The key to making this possible is that the land access laws in Scotland allow you to walk almost anywhere - and you can also camp almost anywhere along the way.
I walked the Cape Wrath Trail this northern summer in 18 days (with resupplies every 4 or 5 days), as part of my section-walk along the length and breadth of Scotland. The Cape Wrath Trail was easily the most amazing adventure I've had in the UK. I'm planning to do it again in 2023 by a different route - and not during the midge season this time

Over to eggs...