I think the 'two hours' refers to the absolute maximum time the interview can take, the time to allow for in your schedule, if you have one. My interview took slightly less than one and a half hours. I was also interviewed alongside one other applicant, which I think is common practice.
The interview consisted of a short written test which was relatively simple. I think half an hour was allowed, but we both finished sooner. I am British but my fellow interviewee was Polish. She had little trouble with the test and I discovered her English spelling was better than mine: I still can't remember how many Ms and Ts there are in 'commmitttee'!
After the test we went through it together with the person from the school, comparing and discussing our answers. Getting some answers wrong was no problem. I think they are looking out for the right attitude rather than faultless knowledge. The hardest thing I was asked to do was draw a timeline.
The representative also gave us a book list and a sample timetable for the course. She made an effort to make sure we understood the nature of the course so we could decide whether or not it was really for us.
If you are enthusiastic, have a drive to teach English and have a fairly solid foundation in explicit knowledge of English grammar (though your knowledge can be FAR from comprehensive) I'm sure you will be accepted for the course.
During the interview you should be given a suggested list of teacher training and grammar books to prepare for and use for the course, and a sample timetable. I have found 'Learning to Teach English' by Watkins to be well written and concise (to my mind). I have also bought, but not yet read, Schrivener's 'Learning Teaching' which seems to get only positive reviews. The book list suggested that to buy or get access to one title would probably be enough, and advised to certainly not get them all.
I wouldn't worry about your interview. I'm sure you'll be fine, and it is likely to last significantly less time than two hours. Remember the interviewer is there not just to test you but to answer any questions you have about the course. Good Luck!