You can see here geological map of Poland without trietariy and quaternary deposits.
Green colour indicates Cretarious deposits that are in 90% chalk. Blue colour indicates Jurassic deposits that are also limestones but rather rocky of coral reef orgin (for example forming rocks north of Krakow).
But of course in the lowlands chalk is covered by trietary (land) and qaternary (glacial) deposits (sand, silt, clay etc.) that can be 500 m thick in some places. Sometimes, where it is near to the surface chalk can be found in the river valleys (like in Milelnk at the Bug river about 150 km east from Warsaw).
In the uplands Wyżyny) chalk hills dominate (excluding Swietokrzyskie Mts. that are of Paleozoic origin) but also are often covered with loess deposits that are 5-10 m thick and chalk is found often at the slopes and escarpments and of course in quarries.
Places where chalk is at the very surface and at the fields you can found white rocks etc. are the Chełm region and some places between Krakow and Kielce.