In reply to Run_Ross_Run:
You're right, the canal tow path is tarmac from Carnforth to just south of Lancaster, but elsewhere it will be grassy. But generally it's not too muddy and we're about to have some dry weather from now to the weekend which should firm it up.
Obviously you can follow the route of the towpath all the way from Kendal to Preston, but you need to have an OS map with you. There's quite a few places where a quiet lane will short cut where the canal meanders and there is also a crossing of the A590 and the M6 near Farleton where you need to use an adjacent road bridge to make the crossing.
If you've got any other specific questions, I'll be back this evening.