Hey there I'm only in week 2 of my primary placement so not at the same level as you but I think behaviour management is going to become an issue. I'm the same, quite quiet and shy and I find it hard to discipline the kids (although I have no probs with my own children!). The low-level disruption in my class is an issue although I think I have made small steps in dealing with it, but today I had a child openly defy me and refuse to do the work I had set him. It was an observed lesson and my mentor said that I dealt with it well initially by not backing down and giving him the choice of either getting on with it or staying in at lunch, but I didn't follow it through enough, it escalated and the child ended up upsetting another girl. My mentor is really good and has come up with some strategies - I just need to have the confidence to see them through. I think part of my problem is that I want the chn to like me and even though I know they won't always I find it hard to be firm. Some of the strategies he has suggested involve following the behaviour policy to the letter, having the steps clear in your head as to how you are going to handle issues with behaviour - even writing down speech bubbles with things you are going to say. As the pp has said, it is an act. Probably not much help, but you aren't alone. Behaviour aside, I love teaching!