Johhnyp, I too have mixed feelings about the slabs. The Dark Peak was my backyard growing up and I walked every where with a couple of friends. It was foolhardy to the point of idiocy to walk alone in those days.
Without the slabs there is no way I would have walked it on my own - a twisted ankle and you're stuffed, There still is no mobile phone coverage in the area by any network. The yellow emergency phone at the Snake Road is a satphone! that said, on Kinder midweek and in term time, with 20yd max visibility and horizontal rain (what a welcome back after 40++ years!) I still met more people than any other week on the PW - almost more than the rest of the walk!
Mobile phone cover is patchy all along the PW, and no one network is best. In the dales you need to be on O2, in the Cheviots on Vodaphone.
The "mature" slabs are remarkably unobtrusive, below the level of the surrounding heather and snaking across the moors finding the driest route! Newly laid slabs are pale and still surrounded by the peat morass made by thousands of passing boots. Beware the flooded half sized slabs in the half mile north of Hadrian's Wall - one misstep and you're thigh deep in the bog! I was lucky, but I met the consequences!
If you need them, there are outdoor stores in Hawes and Alston. The Pen-y-Ghent cafe in Horton also stocks some useful items - don't forget to sign the book!
Enjoy your walk, and I hope the weather is reasonable. I had a week of heavy rain, one of hot sun, and another of heavy overcast. The sun usually coincided with the biggest climbs! I even went over Cross Fell on the hottest day of the year. Exhausting!