There are a vast number of Internet sites now dedicated to Metal detecting. I list a few of them here that members of SHRADS have found very useful.
Portable Antiquities Scheme The Portable Antiquities Scheme (PAS) is a voluntary scheme to record archaeological objects found by members of the public. The Scheme also has an important educational role, enabling children and adults alike to learn about archaeology, get involved, and bring the past to life.
National Council for Metal detecting Site run by Detectorists for the recording of finds
UK Detector Finds Database Site run by Detectorists for the recording of finds
Old Maps site Useful site for showing how the sites looked 100 years ago by the use of old Ordanance Survey maps