What bats do I have, then?

[ChemicalChaos]

Looking out my window in rural south Cheshire (near Nantwich), I very often see bats flitting about the courtyard. I can never get a good glimpse of them, but they look about the size of a blackbird with their wings spread. Does anyone know what they are likely to be?

Sadly I've no idea where they nest, or I'd attempt to get some photos.

[ChemicalChaos]

Thanks, those sound really cool! I'll look at getting some