Venom,
Camberely is not exactly flat , 2 loops with a shortish hill on each, the rest is undulating (but not as bad as Windsor).
Some of it is on residential roads but there is normally a good turn out.
Organisation is excellent (little queuing to park,adequate toilets,plenty of drinks)
and I've done it the past 2 years in my marathon build up and ran a pb both times (although I subsequent ran faster at Bracknell - end of April).
2 years ago it was freezing and snowing ....