Why don't you listen and analyse your own speaking?
This was your first debate in class and you only had 10 minutes to prepare, so I think you did very well. Also it's very difficult to speak when you know it is being recorded, so I think you may have felt a little nervous at the start.
I managed to write down some of the "typical" speaking mistakes that students make, and we can go through those in the next class. However, you might find it useful to listen to yourselves, and think about your fluency and accuracy. Notice where you make mistakes or what you would like to improve, and see if you can work on that.
Click here to listen to the debate
Unfortunately, with all the pressure of the recording and the excitement of the congestion charge(!) you didn't have time to work on using those great "discussion phrases" that we looked at in class. Perhaps you could listen and think about which phrases you could have used.
Recording your own speaking every few days or every week is a very good idea as it helps you to focus on your mistakes at home. Then you can try to avoid these mistakes when speaking in class.