What you're looking for, I think, is a 'licence to extract', your local authority should be able to at least acknowledge the existence of such a thing but it's entirely possible that they won't issue one as the local refuse facility is run by a private company and/or they already have contracts in place.
The operators of the site are not likely to be happy to allow you to rummage through as well because elfin safety (not unreasonable at my local one, they have great big open topped contaners and falling into one of those or having a pile of crap fall onto you would not be good for your health).
It does hurt though, seeing all the 'stuff' thrown away, so much of it either easily repairable or not even faulty, just replaced because fashion or 'too old'.