If you catch the bat while it is sleeping during the day, like if you see it hanging out in plain view, they're very easy to catch. I've caught them in my parents' old house where we routinely had a colony living in the roof and once every few years a few would escape into the house. If they are hanging, you can just slip a wide mouthed jar over them and slip something flat under them to get them to shake loose. They'll wake up then, but at that point they're in the jar and you can let it go outside. Since it's winter, it will probably die, but it will be out of your house.
If you can find where they're coming in, put a light in that spot, like a small lamp and leave it on all the time. They will be irritated by it and will move away from it and quit exiting there.
At my folks house, they wound up spending about $1500 with a pest control company to have these special louvers put on the spots of the roof eaves where the bats were getting in and out. The louvers were one way, so they could leave, but couldn't get back in. Fair warning, this can't be done in the summer months when they're breeding because they'll wind up leaving the babies in there and not being able to get back in to care for them and you'll have a roof full of smelly, dead baby bats.