The courses are a couple of steps up from Thetford. have you ridden in the north downs before? The courses have 'alternative' lines round the bigger technical features but if your in close proximity to other racers you dont always see the signs so if your happy on technical features (small 2 - 3 ft drops, big bombholes and fast descents) youll be okay.
The courses are hilly, lots of ups and downs. rd3 has over 1000ft of climbing per lap.
rd2 at Ash ranges is an amazing course, was complicated last year by the snow and ice only partly melting producing a combination of ice snow and gloop in some sections whilst remaining dry in other parts. The course goes past huge targets where the army train, a bit unsettling when you can hear live ammo being fired nearby and you are right in front of the bullseye.
Hope that hasnt put you off.