Have had 2 days off since I started in June. Both caused by a bad cold/flu, although if I'm honest I probably could have struggled through the second day. Then got told to go home another morning a few weeks ago as I'd been sick twice at work in the hour and a half that I'd been there.
It's pretty lenient here though, and I work in an office on my own, so nobody would really notice if I'm not around. So it's very easy for me to just take a day off if I feel rubbish. I try to avoid doing that as much as possible though.