I have done this a good few times
Cocker Spaniel and sort of did it yesterday
Parked in Chesham Did not take tube even though I have a free pass.
Walked to Latimer house, Turned left past said church and up the hill and back through woods
The real delight of this walk is I think that you have a massive verity of scenes ( River, Corn fields, Field of docile cows, and lovely woods ) and that one can look across the valley and see not a car or house anywhere.
( when we are back to normal there is a lovely pub on Chorleywood common)
Attached PDF showing route