Thank you for he info. I'm dreaming (for now) about coming back to Poland, but if I do it I would like to have my own business. So I thought about the café, but I see it might not work.All I know about is teaching languages.
There is so much available in Poland now. There are also many coffee house chains.
Just expanding on your idea, I think the theme of Supper clubs in tandem with a language/cultural evening could work in Poland. This way the person has an opportunity to eat drink and socialize in the language they are learning. The supper club does not need a fixed premises as it moves location. here is a link