For anyone who is forced to go up to the Lakes after work on Friday, or anyone returning on Sunday for the Patterdale meet, be warned. They are completely closing the A66 from at least Scotch Corner to Bowes, and probably other sections between Bowes and Penrith from 8 pm Friday night through to Sunday night / Monday morning.
So the most sensible way, both late Friday night and returning Sunday, is the M6. Going up Friday in the middle of the day, or returning Monday should not be a problem (based on a trip up there this weekend).