We recommend that you avoid "Flight Attendant Interview Preparation" courses.
In-flight English is an English course for cabin crew that allows you to discuss and practice the language used during in-flight duties and an airline career. If you take this course you will have plenty of practice answering the types of questions that come up in airline interviews, but the main focus is on improving speaking and listening skills. There are hundreds of "flight attendant schools" offering interview preparation classes and they are generally not approved of by airlines.
Often the content of "Flight Attendant courses" aimed at job seekers is not useful and you'd be better off:
If you want to be a flight attendant, and your English is poor then attending a mock interview course isn't going to cover your bad English. You need a well structured English course like In-flight English that leads to a recognised certificate of English proficiency.