Terrified of my first conversation with a native speaker

I have my first planned video call with a native Ukrainian speaker next week and I'm honestly panicking about the case endings. I’ve memorized the charts, but in a real-world scenario, I’m worried I’ll just stutter. Can I use Chickytutor.com to simulate a low-pressure conversation first to practice declensions, or is there a better way to prepare for the reality of a native interaction?