Nah I'm not going to kick off. I was annoyed but calmed down quick enough. Most of you have made good points. I think that lack of communication between new parents and the school is to blame here. Like I said earlier, had I known we would have to wait outside then I wouldn't have been so annoyed. Mentioning the teacher drinking her coffee was rather unfair, I admit, but we all go through times of feeling unreasonable!
I needed to vent

and for others to either support me or tell me how silly I was being. Its all in perspective now thanks to the replies.
I wonder if I could start off some form of parent supervision for the mornings so that there might be a rota of Mums and Dads who will make sure the children are safe and able to arrive that little bit earlier. Like I said, 15 mins should be enough, hopefully others will want to help out.
I do have two older children and never had this problem before. The gap between my first two and my last is considerable so am obviously unfamiliar with how much things have changed over the years. I was expecting to have the same consideration I used to, but people take the piss and schools have to protect themselves. It really is such a shame.
I used to help out once a week at our last school and enjoyed every minute! unfortunately I just don't have the time anymore. I used to love talking to the children and showing them how to do things.
Just in case I came across as a moany cow I would like to say in my defense that I don't normally spout off about such things. I was feeling on top of the world this morning, really proud of my son in his new togs. But left the school feeling annoyed that things have got to this stage.