I would add to the list:
The A65 Skipton to Kendal road - good surface, plenty of bends, great views of the limestone country of North Yorkshire, good places to stop. Can sometimes be a bit busy with heavy lorries and farm traffic. Also - well worth taking the diversion down the Lune Valley to Lancaster.
The A66 down the Eden Valley from Penrith to Brough via Appleby-in-Westmorland.
Another very scenic route the A701 which runs north from Moffatt in Dumfrieshire towards Edinburgh. On the way you get a great view of the Devil's Beef Tub once used by Border Reivers to hide stolen cattle (hence the name) and along Tweeddale through Tweedsmuir (John Buchan country). An enjoyable road on a good day.
