Hi Nabs
The law in England stipulates that we need the landowners permission, and that's it. Some areas are covered by Bye-laws, (such as old gunnery ranges), and digging is illegal, but this site isn't covered by such laws.
As for the military or police, the military aren't bothered as it was them who dumped it 65 years ago. The police would need to be informed if we found any items covered by the strict gun laws here in the UK. For instance, any firing blocks or barrels that could be reconditioned and used come under this law. As a responsible group, we would hand over any item covered by the firearms law but, as yet, have not found any such article so haven't needed to.
We do clean up the relics we recover but only to ensure they do not continue to rust away. All items are kept in our own collections and, at frequent intervals, displayed at military shows and leant to museums. In 10 years of digging and recovering WW2 relics I have sold FOUR items in total. So in answer, to your last question, no, we don't sell the items we recover.
We're about preserving history, not selling for personal gain.
Hope that answers everything.
RRPG