Just get someone to show you the labarynth. We measured one of the tracks at over a mile long, and theres at least 4 different ones all within an area the size of a football pitch!
You can do it without any prior knowlage, but it takes time and a lot of trial and error. I've ben about 6 times now and can just about string a route together.
If you like views and isolation go for the Chilterns, if you like singletrack, small (and soem very big) jumps and corners and don't mind the odd 5minute que for a downhill section whilst the group ahead faffs with their travel adjustable 'rigs' and complains about their adjustable seatpost being jammed again go to Swinley.
I'm dead on half way between the Chilterns and Swinley (about 6 miles ride/drive to either). The Chilterns barely get a look in!