Ship - There are folks in the UK who are experts and masters of this technology both in use and in terms of equipment making.
You will want a detector from a company in the UK if you are buying for that area of use. They have gear and auto id programs
that are dedicated to european bat species, much like we have detector companies here that are focused on our bats of North America.
I would look at these folks, and if you are part of linkedin, check out the BCT (bat conservation trust) closed group on there. Again, what
we might recommend might not serve you well at all, though we have great companies here that make detectors for use the world over
you will be better served by looking at locally produced and local information from colleagues in this case.
http://www.nhbs.com/site/alana-welcomeHere even regional differences can cause issues within North America, many species of bats will not identify properly with auto-id programs
(even costly ones) and self analysis of calls can take years and even decades to master.
Not many in our industry use them because you don't need to identify the species to perform exclusion (something that requires a license and permits
in the UK just to look at bats in most cases) and second because the gear doesn't help with performing exclusion.
The bulk of acoustic monitoring devices in this country are sold to government biologists, biological consultants and the like, as there are always biological
studies going on, and bats are studied most often with acoustic monitoring equipment and of course field studies with mist nets and harp traps.
Hope that helps, this technology is well used in the UK and you can get small handheld units that are fairly cheap, they don't do many of the things the more
expensive models do, but they will get you species id in many cases.
Where you are there are undoubtedly many many bat groups that take folks for interpretive walks and bat detector walks, I know quite a few licensed bat workers
through various groups and know this is a common summer activity.
Look into them, they will give the best info and help you out!
Best,
Justin