The key issue is not so much whether the site is brown or green field, but whether it lies in or out of the village boundary as defined in the local plan. Since it’s outside, any proposal simply to build a new house will be up against strict policies of restraint. Sometimes restoring a brownfield site can be sufficient reason to overcome those policies. Government guidance defines what it actually calls “previously developed land” and excludes agricultural buildings or agricultural land. It also excludes sites where former buildings are so derelict as to have blended back into the landscape. The former barns, therefore, don’t help you. Unless the sand quarry had associated buildings that still remain, it doesn’t help you either because the definition only covers buildings and associated land. By all means check what your council’s planners think, but this appears something of a long shot.