If you can't handle a bunch of kids trying it on and giving you a bit of verbal then I do think you need to toughen up a bit mentally and maybe go and sit in a state school that has a bad reputation and try and see things from another perspective.
I went to a horrendous state school myself and I myself was no angel and I had my moments but maturity does come and with hindsight I know why I had those moments. I often got bored and detached from lessons that were just monotonous and I became distant to the teacher and their methods. I'd then fidget and get distracted and do something to keep myself awake during the lesson.
If a pupil asks 'why do we have to learn this crap?' then answer in the right way and put a bit of back information on it and try and add your own story on it so that its not just 'because you have to do so'. The thing is, loads of secondary school pupils are craving to be addressed like adults but feel they aren't by their parents maybe or the school or even the system and government and we've all been through that phase when we were younger of having an attitude.
Im looking forward to my PGCE and whilst I will at first be nervous about getting up in front of a class to teach I will learn and be dedicated to not only the task of expressing my subject knowledge further afield but also supporting them and helping them gain an understanding of what matters and how things are.
I was nervous when I first got in a car, the roads full of other drivers tailgating me trying to bully me into speeding up and doing what they wanted. I overcame that and I will use my passion to become a teacher to overcome the hurdles that teachers face on a daily basis. Of course its not going to be easy but thats life, its never easy.
You go into a corporate scene and you'll have adults stabbing you in the back trying to climb the career ladder and make their big break. They'll do that behind your back and they'll tell your colleagues things about you or talk about you at the table at lunch to try and get their cliques going. Thats just life. Be prepared for people to say bad things about you.
At least school children are straight up with it and will tell you its crap if its crap and be honest. Its good to be a good talker but I see nothing wrong with asking them 'what would you prefer? why is this not coming across right for you?'. Listen to them and reason with them and understand that they are human beings who should be respected. As a teacher you have a lot to learn as well and there will be children in that class who learn at home about the subject you teach and know more than you.
I may be fortunate in that my subject can be both academic and vocational (computer science) so I'll most likely be able to take them into the computer room, get them involved in things and alleviate the boredom somewhat from a normal classroom setting. I think a lot of pupils get bored and speak out because they want to test teachers. I will happily cater to different learning styles because I myself struggle to take things in from just having someone in front of a whiteboard speaking. Different approaches reach different people and keep them interested.
YouTube videos to show things, props such as devices and hardware, group sessions, get pupils involved and if they make a mistake so be it because thats life.
I remember one teacher I had for history and she said to us at the beginning of the year 'if you do all your work in the week then Friday afternoon we'll watch a film in that lesson'. She said to us that life is about working hard and playing hard and that if you put in the effort you deserve to reap the rewards. Everyone worked their socks off in the class, people got involved in what to some is regarded as a boring subject (I love history however :P ) and we watched a film every week. I ended up with an A in History and most others in my class had at least a B or above in a state school that had a bad reputation at the time.
Be someone who cares and be someone willing to go that extra mile to make a difference. You put in the effort and you'll reap the rewards as well when you get pupils thanking you for believing in them.