What you said
Children behave completely differently for different teachers. If you go in and are clear about your expectations, then you'll be fine. My class is absolutely horrendous to substitutes if they are not on the ball. As for their uniform - I'd leave it. All you're going to do is sabotage relationships with pupils. It's one thing picking up on disruptive behaviour that affects learning. It's quite another to go about sorting out your own pet peeves.
The expert view
Great question: the simple answer is NO NO NO, do not go down a notch or two. As long as you work within the letter of the school behaviour policies, then I would recommend that you set your boundaries and consequences precisely as you see fit, and not based on the estimated average of the rest of the school.
Which type of teacher do you want to be? The one for whom they bounce like beans, or the one for whom they work and learn? It is a question with an obvious answer.
In your career, you will see a lot of bad teaching as well as good; well- run schools and poorly run schools. Your job, however hard, is to be the best you can be for the pupils, and for your sanity. What you do is fix the small scrap of land right in front of you - not the world, just what you can manage. That is all any of us can do.
Tom Bennett's latest book, Teacher, is out now, published by Continuum. Post your questions at www.tes.co.ukbehaviour.