The Lutonski road lies somewhere between Blaviken and Yspaden, and its named after Luton (coast town in Arc Coast) so most likely cutting across parts of Redania and Kaedwen via the Kestrel Mountains. There are apparently a number of small villages along the route and winter weather is a problem.
"I'm making my way to Yspaden, but I don't know if I'll get there before the snows block the way. I might get stuck in one of the little towns on the Lutonski road."
- - pg.77, The Last Wish (UK edition)