It will have to be fixed before you drive it very far. If the battery light is on the alternator is not charging, your not going to make it very far before the battery goes dead. Your local parts store will be able to test the alternator on the car, most if not all will do it for free. Based on the battery light I am confident it's the alternator, but checking it never hurts.
If you can change the alternator yourself you may still be able to get one if you act fast. Most part stores here are open until 6 tonight. If you can't change it yourself I am not sure you will get it repaired before Thursday. You can try some of the Towing companies that have garages as well. Because of the towing running 24/7 most usually have someone that can repair cars available even on holidays.
You can also check the wires going to the alternator, you will have to jack up the car because it's on the back side of the engine on the bottom. Make sure the small wire is connected to the alternator, I recently had one of these cars that the wire fell off so the alternator wasn't getting the charge signal from the PCM. It takes about an hour to change the alternator with the car on a lift, so maybe 1.5 - 2 hours if your doing it with jack stands and don't have the best assortment of tools. It might be a pain but you should be able to do it with a basic tool assortment.
- Disconnect the negative battery cable
- Loosen the jam nut and the adjustment bolt. Regular wrenches will work for this but a 1/4 inch drive or a stubby 3/8 drive ratchet will make it easier.
- Raise the vehicle and support it on jack stands. You can get away with only jacking up the passenger side.
- Remove the accessory drive splash shield, ratchet works best.
- Loosen the lower mounting bolt
- Remove the belt, I would usually tell you to replace the belt while you are there but it's behind another belt so it will add extra time you may not have.
- Disconnect the small wire going the the alternator. This is the wire to initially check to make sure it's hooked up.
- Disconnect the big wire on the back of the alternator. Make sure you did step one before doing this!
- Remove the upper and lower mounting bolt and move the alternator off the pivot bracket
- Remove the pivot bracket
- Remove the alternator through the wheel well, it can be tricking to get it turned the correct way to get it out but you can get it out without taking anything else off.