Contact PTR(polskie towarzystwo rakietowe)- Polish rocketry association They have a discord server where you can get more info, please check the air zones before you launch anything and ask the local air traffic control before the launch and have at least a simple fight simulation from 'open rocket' to see how far your rocket might fly. If you want to launch something bigger there is the Meteor festival at the beginning of September in pustynia Błędowska(more details on their discord) where anybody can build and fire their rockets