That's really cool that You will be in Poland later this year. I am originally from Poland and follow the championship closely. It seems to be struggling because of funding, but there are some semi-factory efforts.
Grzyb-Suzuki Ignis Super 1600
Frycz-Fiat Punto Super 1600
Kuzaj-Prodrive N10 Subaru Impreza (their should be a whole host of N10 Imprezas this year)
I suggest going up to Northern Poland for the Rally of Poland (full gravel) around Olsztyn, which is a Coeff. 20 round of the European Championship. From what I've read, this event is currently trying for inclusion into the WRC. It's going to held June 10th through the 12th. Although the Rally of Poland was held in Klodzko (asphalt), last year it attracted Simon Jean Joseph, Bruno Thiry, and Luca Pedersoli in the winning 306 MAXI. Good Luck!