Is it the first time that light has been on? Sounds like the battery is flat, and the alternator hasn't charged it, which is the reason I asked if it's the first time it's been on.
Have you a multimeter? To test the voltage in the battery, mine normally reads 14v with ignition off, 13 with ignition on, and normally 12.2ish when cranking, any less than that normally means battery is duff.
Can you use another car to jump the car off? To see if you can get it started first of all, if you can and the battery light stays on, then the alternator sounds duff, have you checked any connections, to the battery at least? Loose connections can cause problems too.
Where are you based? Someone close maybe also be able to put it on there VCDS lead.
Hope I've helped