Start at the top of Apsley Woods and just ride about – there are trails going off in every direction every few yards.
Its a small area bounded by roads, so you will only be lost for a few mins.
Its pointless trying to give you a route, you will be lost in 10 yards. Just pick ones that look interesting.
Mostly sandy / rooty / wooded singletrack – pretty weather proof.
Ive bumped into the warden once in 50 rides, but helpful if you have a fiver should you need to pay him. ( I do have a season ticket )
There is some very good singletrack there, not hard to find if you just ride about looking for it. Great fun.