I'd second the comment about having a word with your neighbours. It's not a legal necessity, but a quiet, friendly word of explanation is less hassle than a reported firearms incident. Maybe invite them to have a go, or see your set up.

Remember, to the layman, a gun is a gun, and they'd be quite entitled to be alarmed, in the absence of any more information. It could also be worth letting your local Plod know when you're shooting. They'll give you an incident number, which you can shout at the armed response team if they get called out.