If you need to travel on that date, check whether KLM serves other nearby cities, ideally in Poland, that would have train service to your destination. If your flight is cancelled, ask to be booked to such a nearby place if KLM cannot rebook you on another flight on the right day to Wroclaw. You should plan to pay for the train ticket yourself. Alternatively, if the flight is cancelled, you are entitled to a full refund, so if the new flight is cheaper, it might be worthwhile (and easier) to purchase a new ticket yourself.

Also, familiarize yourself with the EC261 regulations. You especially have protections if the flight is cancelled within fourteen days of departure. There's a big sticky thread in the BA forum here on FT that gives definitive and detailed information.