To help you find suitable walks here’s a rather rough-looking interactive Google map. Just click on the lines and blobs to get more information about that walk. You can use the menu at the top of the page to print off pdfs and to look at more detailed directions. Each walk description has a GPX map attached so you can follow your progress in real time – if you have signal. Failing that please use an Ordnance Survey map to check the route (OS Explorer 147 has them all).
The walks around Shoreham, Downe, Cudham, Otford and Knockholt are on North Downs chalk fairly close to or on the escarpment itself. They have a different character to the more wooded southerly routes around Ide Hill, Westerham, One Tree Hill and Sevenoaks, which are on the Greensand Ridge.