Try to ride the route at least two days back to back for practice. It will give you a sense of how long the ride will take and the traffic conditions.
Several things you probably should get before the commute starts - full coverage fenders (make sure that they will fit on the bike) even if it's not raining just running through one puddle can give you a skunk stripe up the back
A rear rack and at least one pannier (you might want to carry a laptop, spare clothes, jacket, (do they still use books) and whatever other supplies you need for class. A messenger bag would work, too - but it might get hot.
Lights - Front and Rear - the bigger and brighter the better! A headlight good enough to actually light the road (if the magicshine is still for sale it seems to be the best for the price). For the rear, possibly a Planetbike rack blinky 5 (has both rear reflector and a rear light) a PB Superflash, a Portland Design Works Radbot or Safetyzone. Check the electronics, lighting and gadgets forum for more.
A Big Lock - seriously, this is your means of transportation, you want it to be there when you show up to ride home.
You don't seem to mention where where your from, but if it gets cold, you should check out the winter cycling forum. If you plan to ride in snow and ice, you should look at getting your studded tires now - if you wait until late November, you may find them on back order. You might also find the same thing with higher end lights like those for dynamo lighting.