Question : Is there another local airport that can get you to Warsaw?
Answer : Lucky for you, there is another airport near London. London Heathrow Airport (LHR) is 22 miles away, and over the next few months, flights are being booked 90% cheaper than flights from London City Airport.
Question : How long do most people visit Warsaw?
Answer : Of course you're not most people, but if you were, you'd stay roughly one week.
Question : If your plans are flexible, have you considered changing your departure day?
Answer : Monday is your lowest-cost day to fly in March. Being flexible with your travel days garners even more savings during booking.