The best thing to do is simply tell your story as you have experienced it and how it relates to what they want to know. All it is really, is a conversation. Since it is only 2 - 5 people, it would not be too stressful. We had to do this for an International language school I attended. They had to be evaluated occasionally to keep operating.

Really, all the want to know is if you have been staisfied by your T's services and the company or organization he/she works for I am guessing.You will be great I am sure. Would the office staff be able to inform you of what the interviewers usually look for? What questions they usually ask? It could help you feel more comfortable in answering if you know what's coming.