Thanks for the tips so far, guys.
Do keep them coming
We haven't decided on Wales yet, as it does sound tempting but we would prefer to spend some more of our time up north. So most likely we'll keep Wales (and Devon and Cornwall) for another visit.
We more or less have a rough route figured out. Not sure yet about the Folkstone to Stoke-on-Trent route, but it will most likely include photo stops in Stonehenge and Avebury. Suggestions are still welcome. From Stoke it'll go through the Peak District national park, up to the Yorkshire Dales and then west to the lake District. Over Wrynose and Hardknot, then with a small tour passed Derwent water across to Hartside and straight to Hexham. Along Hadrian's Wall and towards Dumfries. From there up to Loch Lomond, but not quite sure on the route here yet either. Let me know if you have any good ideas.
From Loch Lomond towards Loch Awe, and along the south side towards the coast. Along the coast, around Loch Leven then over Fort William to Mallaig for the ferry to Skye. Then after a tour of Skye across the bridge to Kyle perhaps a visit to Eilean Donan Castle. Back north, across to Aplecross and with a tour along the coast to Kinlochwe. Most likely a small detour to Loch Maree for some photo opportunities. Then back and across the Kinlochwe Heights to the east and via Muir of Ord towards Loch Ness. Along the banks to Fort Augustus.
We're not sure yet on how to continue from there but we would like to go towards Montrose as there's a friendly Belgian guy running a biker friendly B&B
Then south for a cultural stop in Edinburgh.

Through Northumberland to Gateshead for some piccies of the Angel of the North (a must for fans of the "Bende van Wim" motorcycle touring show). Down through the North York Moors to Nottingham and Sherwood Forest (to please the misses

) and via some still very blurry route back towards Folkstone.
Oh my, that sounds like quite the undertaking

and all this hopefully in 12 days.
So please feel free to point out any boops I made so far or to make suggestions for filling in the blanks and blurry bits.