Blimey graham.
TBH, you can start from multiple points (high beech is a favorite because of the parking / tea hut) but there miles of singletrack – you could be there all day and never ride the same trail twice.
I couldn’t describe a route to you, as its a bit like joining up trail A with trail B, then maybe today we’ll put trial F in the middle and it relies on lots of local / visual knowledge – it is miles of trails through trees so everything looks the same after a while.
On the plus side Epping is intersected by A roads and because of its condensed nature your never really more than an hour max from High beech. My advice for anyone “new” to the forest is to join an established/knowledgeable group for the day, or just ride and follow your nose but keep a smart phone/map handy so you can find your way back.
Just ride every bit of singletrack you can Graham, and enjoy. I normally ride wednesdays so would have been happy to offer to guide you but I’m working away this week.