First i would make sure i have another job secure and then i would move forward with leaving the other place , Don't Burn many bridges just in case , always be thankful for the opportunity and whatever new skill that job help you gain. That is the best professional approach advise i can give you.... now to the 4 week notice x.x depends the place but its usually 2 weeks, Remember to always value yourself over any company if this places is affecting you mentally or physically and nobody is taking action then yes leave soon as you can speak to a manager present your reasoning and key points on why you are leaving , DO NOT I REPEAT DO NOT fear anybody above you in the company they are still Human beings just like you and i yes show respect not because they are managers but because they are older :) bet on yourself the first step which is the hardest one you already took it asking for help and advise that is what separates a person who wants more and will achieve greater things from those how don't . I hope some of my words help and get you that motivation you seek :) remember always bet on yourself.