Don't rely on Centrelink to support you.
If you are straight out of year 12 chances are they won't just give you money. They will judge it on your parents income.
The only way to get around that is be over 25 (22 with the new budget) or work for 18 months (2 years with the new budget) and earn a certain amount. Otherwise you are still classed as dependent regardless if you live at home or not, or receive money from your parents or not.
The only other way around it is to prove that it is unreasonable to live at home, where your parents have to declare that they will not let you live at home and refuse to support you, or you have the show a youth worker that the situation at home does not allow you to study. Its not just like you fill in a form and they accept, they will call your parents, need written statements from them and a third party like a counselor and you need to go to an interview. This may have changed since I went through the process but don't turn up to Canberra and expect to live of Centrelink as you may be sorely disappointed, as well as hungry and homeless.
If someone has already mentioned this or you have looked into this and solved the problem, then ignore my comment.
In regards to colleges, I was a local student so I didn't get in :mad1: but the only financially viable ones for me would have been Fenner or Burton and Garran. If you are wanting the whole 'on campus' feel Fenner isn't probably the best bet, as it is a 10 or 15 minute walk to the campus. I believe for those you are looking at about $160 a week and they are not catered.
Alternatively you could live with family, although that would be no fun, or share. Sharing a house with students or other people is quite common in Canberra, as the house prices are quite high and there are many students. The suburbs in 'North Canberra' which is where the uni is, all often have share housing. If you are lucky you could get a alright place for around $100 a week, and quite a good one at $170 a week. As a semi rule, the more people who live in a house, the cheaper the rent, so you may be able to cheaply live with four other people and it would not be like a college but still studenty. Also the rooms in the colleges are quite small, so with a house you may get a bigger one as well as the whole lounge room etc thing.
From your comments it appears you have not been to Canberra. Perhaps you are mistaken for what it is like and you should visit it before you decide to move here for three years.
There is not real QVB type place or train system. From ANU you can walk to Civic, where they have semi upmarket places, but it is not the whole inner city feel. Its just a mall with some outside coffee shops and a merry go round. Canberra is very different from most other Australian cities. Consider doing your research before jumping the gun and telling everyone you want to come here.