I just wonder if you speak Polish, if the instructor will speak good enough Polish, and is there a Polish theory exam? That could be the tricky part but its a good idea.
The written component of the driving test in Poland is so notoriously arcane that even Poles with higher degrees have difficulty understanding the questions, let alone answering them.
The system of back-hander payments also seems to remain in force in Poland, though you have to be born here to understand how to offer one without being arrested for attempted corruption of a public official.
Better to do your test in the UK, where you have the added bonus of being able to understand your instructor (unless he/she is Polish, which is increasingly likely in our wonderfully multicultural land).