There's definitely a Berlitz school in your town. (They are everywhere!) If you go there, you will find a lot of people to speak English with. Generally what will happen is that people will want to practice their Polish, so they want to speak to a native Polish speaker. So you go out to drinks with 5 or 6 Berlitz students, and you all speak Polish for a bit. You help them out with their pronunciation, conjugation, etc. And inevitably, they get tired and switch into an easier language, which is 99% English. Now you are speaking English with native - or at least fluent - English speakers, in person, and getting corrections right away... hearing how people speak English in conversation... chatting comfortably in a foreign language. A lot of people say to watch English language movies or TV, but that's is NOT conversational english. That's a script. Every word is carefully chosen. Chat with the oodles of native English speakers in your country. As someone who has done this personally (been the Native English Speaker for Hungarians, Serbs, Bosnians, Ukrainians, etc), I know it is a GREAT way to make friends, and get much better at the language of your choice.
I didn't even know that such thing exists! Thank you, there are in fact three Berlitz Schools, two of which are within 15 minute tram ride from my dorm. And one is near the airport, so I can ask them about it before my flight to Sweden (very excited! I was never on an airplane! :D). I hate the way I think, but my immediate thought was Knowing my luck I'll be assigned to a group from either Portugal or Saudi Arabia ;).There's definitely a Berlitz school in your town.
(…) which is 99% English.
I'm glad to help! Don't worry about that. You won't be "assigned" to anybody. What will probably happen is they will take your name, or introduce you to a teacher, and you will casually meet a couple of students and see if you all want to hang out together. It's a casual thing, helping people out. Not an obligation or structured study class. my immediate thought was Knowing my luck I'll be assigned to a group from either Portugal or Saudi Arabia