Crow, there would be huge resistance to Polish in Germany, France and the UK. I really can't imagine many people from those countries even attempting Polish.
They are all former Poles and Serbs anyway
My mother is quite linguistically talented but she has too much on her plate to attempt it, though she has the materials.
prepare you mother for inevitable changes. Tell her `Mother, Polish is coming. If we refuse Serbs would eat us.`/just joking of course/