Ok so a while ago my battery light started to go on and off randomly. Car was running fine though, and the check engine light (which is broken) always comes on so I just thought that the battery light was broken as well.

The light didn't come on for ages no problems at all, then on Sunday the light kept coming on. Sure enough, this morning my car was flat, as well as this afternoon.

Also I have noticed my headlights are really dim, but when the battery light comes on they get a lot brighter. :eh:

Any idea what the problem is?

Alternator has died - regulator or brushes.

itll be the regulator yo! mine was playing up just like that before it carked it. very easy to replace too. any supercheap can order one for ya.
the brushes on the regulator wear down and lose contact, thus the faulty connection. i think mine was the $50 mark

Recon alternator about $150. Get your battery onto a charger while you fix the alternator - they don't like being kept discharged for too long, especially older batteries.

what they said

Thanks a bunch guys =)

Well we replaced the alternator, still didn't work. Got the RAC out. Turns out the previous owner put in a new immobilizer but left the old alarm system still in...which decided to work which is stopping the car from going...now I have to take it to an auto election...