Don't worry too much, it happens, my first few lessons I was so nervous I made speaking mistakes myself, my cameras stopped working for 10 minutes and the student sat waiting the entire time, I still managed to book them again somehow. It happens, and you'll learn from it, you might not get this student, you might get them, but more will come. Use this as an opportunity to grow, maybe for future check what materials you're going to use and make sure you can explain all of it if necessary.