Hey Steve,
Do you follow me on Strava? I did Haydock up to Penrith a couple of weeks ago (Day 5 of my LEJOG), stick in a follow request and then nick the gpx file off there.
From Stockport, I’d go Cheshire Lanes out to Knutsford then north up to High Legh, past Lymm, then Culcheath then sort of thread through in a NNW direction until you pick up the A49 north of Wigan. Through Preston (it’s not *that* bad) then turn right at Broughton and into the back lanes that skirt Lancaster, it’s lovely round there. Or just A6 if you want the most direct route.
Lancaster traffic is currently mental thanks to the building of that new link road from the M6 to Heysham so avoid Lancaster if at all possible. Back roads up through Dolphinholme, Quernmore, Caton FTW.
Pick up the A6 again at Carnforth, that bit is fine then there is some lovely back road stuff up to Kendal (do not do A591 to Kendal on a bike!). Over Shap (long steady drag) through Penrith all A6 is fine then turn left at Plumpton and go up the back road just to the left of the motorway, brings you in at Carlisle.
I’ll do the Manc – Penrith bit with you if you want.