There are BCT surveys on for most of the year I find them very entertaining
the one I am involved with currently is a Daubenton survey of one kilometer
of a local river, luckily it starts at a pub and finishes at a pub

The trick is to go to the furthest point while it is still light and mark your sample
points with pegged(white) paper plates so's you can find them as darkness closes in

Contact the BCT these surveys can be used in evidence in development enquirys and
just help us plot the health of our Bat population very worthwhile and gives a purpose to walking the dog