I'm going into the middle school high school building next year, a it going to be as hard as i think it will be?

Not at all , if you're not used to that type of school then the only thing that should be on you're mind ,should be giving your best ,and  putting lots of effort in school . If you're scared or having anxiety over it then just remember that you're awesome no matter what !, "you are definitely smarter than you think and  stronger than you seem ".
I wish you the best ! 

They usually separate middle school and high school.  So you will be doing the work of whatever grade your in.  If you get bullied than just go to a teacher, or stand up for your self most likely you will not get bullied considering that there are lots of kids at the school your going to.