Have a look at this site
http://www.smithsax.btinternet.co.uk/ it's how to build your own humane mouse trap. My mum had some mice in her house, I moved in for a couple of days caught all of them in a humane mouse trap that I bought in a pet shop and let them all out in a big field about a mile away. I was told they were wood mice and they were really cute with big huge ears, nothing to be afraid of. I forgot to add that mice are supposed to hate the smell of peppermint and if you buy peppermint oil and soak some cotton wool in it , place these around where you think they are getting in, it should put them off . You can also buy special pouches of peppermint mixed with spearmint called Mouse Away if you wanted to try that.