For your next lot of payments, you can go to the post office and get a payment book, this will allow you to put money towards your rego throughout the year so it isn't such a bit payment when it comes time to paying it next time around.
Qld do 6 months of rego for all vehicles, the option is on your bill, which didn't come a few weeks before it is due I might add, they are sent out 6 weeks before your rego due date.
If you don't pay by the date, then you will get hit with an extra amount to pay.
They probably won't give you extensions.