I could make a guess and say it is 55M2.
How old is the building?
It also depends on if it is insulated, you can start with the windows, are they new or old?
Different administrations charge different amounts, it is not possible to give you an exact figure but any more information you can give will get us closer to the real figure.
A standard Polish three room apartment should be around 65 m2.
Youre heating is most probably gas and provided by the local council, im fairly sure gas payments are staggered throughout the year therefore no extra costs during cold winter months.
Id estimate your utility bills / month at:
gas 200 pln
electric 110 pln
phone 60 pln
internet 50 pln
water - i have no idea but not much