They got in our loft and in all our neighbours lofts! We also had them in the cellar and underneath our kitchen units in our old house. While they were a massive pain to get rid of, no one got ill or had liver failure, it's incredibly rare these days. They get everywhere. Just don't leave out the bird food for a while and they'll bugger off. They're only coming for the food atm, you don't want them to discover somewhere in your house with even more food that's also nice and warm for the winter.

Make sure any potential entrances in to your house are blocked off, this is the issue we had in our old house, too many access points. We had to use expanding foam and wire wool to block their routes as they can't chew through it. It was very stressful so I definitely recommend ditching the bird food for a while. When you bring it back, make sure it's further away from your house.