I never bought a guide, just read and took notes from the internet. Its easy now, If I'm hiking anywhere I just use my phone (just need a signal) when I want to check out information near or ahead of me, including weather.
When I first did the PW I bought the Harvey Maps, which were fine, although for me, being colour blind (red/green) I could not read them at all in artificial light, e.g. in a pub, just a blur!
I have since bought the A to Z OS booklet maps which I think are great, A5 sized, very much an improvement on the Harvey maps and for me perfect, I can read them in all lights.