Parking can be found in Watts Gallery (GU3 1DQ) in the course of their opening hours (they do close the gates), or simply before the gates if they are closed.
These downs in the prime of the hill are walkable from https://dawududpn000022.blogpostie.com/50348048/the-smart-trick-of-dog-walker-guildford-surrey-that-nobody-is-discussing