I'm not sure what is the source of your anxiety about going back to school. I have been out of high school for over 30 years so I don't know first hand what it's like today except to say I have 3 daughters ages 21, 19, and 15, so I have seen alot as a spectator. That being said, I offer the following advice and you are welcome to take or disregard any or all of it.

Don't put off your homework because it won't get easier by having less time to finish.

If you don't have time to do it right, you don't have time to do it twice. So try your best and if thats what you've done, accept the grade and move on.

Last, noone is really as cool as you think they are, and you are not as uncool as you think you are. It's all perception and only you can alter that. What you think of others is rarely what they think of themselves, and vice versa.

Remember this, even when you look at yourself in the mirror, the image you see is not what others see as it is reversed. Relax and enjoy.