Issues updating to latest version of itunes

I have a macbook air running yosemite which is currently "hired" out from my school. The laptop however is essentially mine with no restrictions being placed and the relationship is similar if you were to rent out a laptop from another place. The issue at hand is that i cannot update my itunes to the latest version for itunes music. The update does not appear in my app store under Updates and although itunes prompts me everytime i open it that there is an update, upon checking the app store there is nothing. I do know that i am required to update through my school's network but i am currently on break for the next few weeks. Is there a way to update my itunes manually without actually connecting to my schools network or any workaround?