I'd troll up the M6 come off at Penrith and drop in on Mayburgh and King Arthurs Round Table, 2 minutes from the junction. You'll not see anything like Mayburgh this side of the Irish sea. This will also put you within striking distance of an easy dozen or so readily accessible sites.
I'd avoid Keswick and the Windemere area because it will be chokka-block with trippers.
Have a good 'un and learn the route cos you'll definitely want to return.

fitz