I live in Walton on the Hill and this (assuming the link works) is my local off road loop.
http://www.strava.com/activities/1075652713
Straight from my front door and takes c.1.5 hours depending on conditions. Obv. can be joined anywhere and for Epsom/Ewell folks maybe join at Langley vale area. It is fun, fast, easy to navigate and could be ridden on a CX bike (I don’t)
Ignore the little detour on Banstead heath – there are some cheeky trails that I was going to ride but just as I started I had my second puncture of the ride, threw my toys and nursed the bike home.
Incorporates some of Zippy’s route (btw Zippy you are missing a lovely bit of track that runs adjacent to Walton heath golf course rather than the straight route across the field and then Banstead Heath – highly recommended alternative).