I've no experience of the FC in the Forest of Dean, but I'm GAGB's liaison with the FC in Dorset. I submit proposed caches to them on behalf of cachers wishing to place there. I do that by email, and it generally takes three or four days to get either an outright approval or any queries about the cache.
Edit: I'm a little surprised that Collingbourne comes under the Forest of Dean!
Do not go gentle into that good night.
Rage, rage against the dying of the light. (Dylan Thomas)