Hi Richard. I did the Ribble Way 2-3 years ago and found it in poor condition, due to both erosion (repeated flooding, not walkers) and state of waymarkers (old and incomplete). Even the original route required road (minor, not A or B) diversions where there were (and still are) no riverside paths, and it's worse now. It's not a route I would recommend, even in its original state c1980s. Of all the LDPs in this region (south pennines, south Dales, Lancashire) it's the one I would least wish to revisit. Much better ones available, just search in the LDP database within e.g. 50 miles from Preston.
Not put you off ? If still keen, email me (firstname_lastname@btinternet.com, care with spelling of my name, without capitals and an_underscore) for GPX tracks and further info. At or after end of this week preferred.
Iain