I'd agree with svDaveC for the most part. From Pirbright A322 south towards Guildford, left at roundabout onto Salt Box Road (Wave if you see me
), left at roundabout onto A320, then immediatly second right into Jacobswell (Clay Lane) Along there until you come to a BP station (2 roundabouts), left just after the BP garage (at the roundabout, New Inn Lane) Up to the A246, towards Dorking (This is where we differ) I'd follow the A246 all the way to the Green Dene turning that takes you up to Ranmore common.
Another way from Pirbright is to head to Foxes corner, left at the roundabout and then next right. Takes you across to the A320. However, not a bike fan of the 320, seen to many plod speed traps on weekends
I'll see if I can sort a map out if you want