There is a mention of the first climb ( Duncton Hill ) but only to say you get the descent off if it. It is the exact route I rode a couple of weeks ago. It’s tough. The first gradient ( Duncton Hill ) is about a steady 6 percent, with an 11 percent step at the end.There are a couple of 6 percents during the ride, then the climb at the end ( Harting Hill ) has a 6 percent start, (until you reach the church), then kicks up to 18 percent for about a quarter of a mile. The Velo South lot mention the ‘kicker’ at Copsale as well, but don’t mention how steep it is ( 12% ) but only for a few hundred yards.
https://www.relive.cc/view/1493205581
Here it is as a ‘relive’ there were 2 slight differences, from the official route ( owing to a road closure at Elmers Marsh) and a 500 yard detour near Horsham, due to an accident, but other than that, it’s exactly the same.