This is a great website for road nerds. www.sabre-roads.org.uk.
Anyone taking their driving test at Sidcup test centre should get to know Crittals Corner quite well, as the lines you need to take through the junction may require some practice. The road markings are a broken up somewhat so it is important that you look well ahead to read the road, and be aware of road users in front, behind, to the left and to the right.
You can view some of the sidcup test routes here.