I imagine everything will be closed the day of or Christmas Eve
Christmas Eve: early closing
Christmas Day: Poland closed
Boxing Day: Poland probably closed
Christmas being at the weekend doesn't help either.
New Year's Eve: find an open-air concert somewhere. if it's cold it will be your feet and ears that feel it. wrap up well.
New Year's Day: sunday (Poland closed)
Church might be a good place to go for company and a little of the festive spirit. i'm thinking english speaking church. there must be one somewhere.