I ride the Lancaster canal a fair bit, it’s pretty overgrown at Preston end despite starting on tarmac. Lulls u into a false sense of making progress, after 5 miles it was so overgrown I was pushing. It’s the knee high grass with about 6 inches width of path at worst, near kirkham.
Lancaster north to carnforth is good, just have to slow down at each bridge as u just can’t see if it’s clear.
Dm me if near Lancaster if u need anything, live just by bridge 118. Good fish and chip shop at packet bridge a couple of bridges north.