Or even, perish the thought, days out in Wraysbury or Buckland fr those in the sarf east. Actually in some ways Wraysbury is good for overhead as there's certain 'attractions' which are good for line laying practice and the poor vis can be good for navigation practice. There's also a few platforms for that authentic practice frustration. Buckland, near Rochester, has a small mine-like sump with pumping equipment. The lake bottom needs good finning skills to not stir up the muck.