I'm planning on leaving work early.
Why are do you plan on leaving early?
I don't have anything else to do here, so I think I'll just go home.
That sounds great. Except we're expected to stay at work during the time we are supposed to be there.
That sounds dumb, I hate this place and there is nothing for me here.
While going home early might be tempting, you should work the hours that are required of you. What would happen if you leave and something at work pops up to do and you aren't there? I wouldn't want you to get in trouble.