Permission to change a roof and add windows (considering buying a house in Poland)

I am at the point of considering buying a house which has had its roof changed and loft windows included. I am not sure if the owner applied for permission for this to be done but will approach him soon. The three windows at the front of the house do not overlook any other property as there is just a forest opposite. There are two loft windows at the back of the house which again do not overlook any other properties, just a field. I understand there are very severe fines if planning permission is not applied for but wanted to know how I could resolve this issue if the owner tells me that permission was not applied for.The materials used for the house are of good quality. Who would I talk to so that I could find out if permission was granted and what are the penalties for not following the rules.?

As far as I know, during the property sale there must be done the property title audit and if there are any problems with permits or associated fees, it will show up and then it's up to the seller to take care of it (or the buyer could take over if they agree on that).