Hi!
I want to go to a flight attendant interview after I'll finish high school, but unfortunately I haven't worked and I haven't volunteered. I know that at the final stage at a job interview you're be asked questions which require to have work experience. Will I have to imagine, like: 'Imagine that you have to handle an unruly customer. How do you resolve the ensuing conflict?' or I won't be asked questions like that?

Yes, you will be asked questions about customer service based scenarios and often giving answers based on your specific experiences. Also, customer service experience is required for most cabin crew roles, so I advise getting some part time work at least... Also, many airlines don't accept you until you are 21 although some will take on at 18. You can start preparing for your interview now - the career advice pages here will give you lots of useful information to read up on.