Could you give a clear concise answer to questions about why you want to teach English, what qualities you think you would bring to a class and why you want to take the course? It's an interview to see if you are suitable for the course. They will want to check your level and see that you are interested and genuinely want to teach. You don't have to be the finished article- that's their job. They might ask you about examples from your learning of good and/or bad teachers/teaching.