You can ride around Hadleigh (not the Olympic course) for a few hours, go to the castle and follow the bridle ways and paths along the coast, Langdon hills is a twenty minute to half hour drive away and mainly hard pack, and after all the rain any non hard pack bits will be a clay ridden swamp..
Thorndon park is a similar distance away and is basically a hard pack loop with loads of cheeky bits going off it all the way round, there’s no proper routes as such with both, you just have to keep your eyes peeled for gaps going off into the trees and scout around..
Ill be going to Thorndon on Sunday if you want showing around, but the recent rain might have trashed some of the better bits, its mainly clay round here and doesn’t do well with a lot of rain..