is it possible to buy land
I can confirm after recent consultations with legal entities in Poland that issues come into play if the land has more than 5 hectares (50,000 m2) that has been zoned as agricultural. If the land falls into this category you will need permission from the ministry, and the application costs about 1600 PLN and can take two months to process.
If the land has 7 hectares for example but over 2 hectares is zoned as park for example you will be fine.
A capable notary will check the status of the land and advise accordingly, if they get it wrong and process an illegal transaction they risk losing their license, not sure what the situation would be for the buyer.