I'm Jason and I work for a company called SEEK Learning, so do take this with a grain of salt but I thought could provide you with some tips to help you in your research.
Have you decided yet if you want to keep working full time or part time while you study, or are you thinking of leaving your job to study full time? Your answer to these questions should probably guide your research when searching for educational providers in graphic design.
For example, you might want to search for providers who offer online or distance graphic design certificates if you still want to work while you study. This is often the path many people take when they're looking to change careers. Alternatively, depending on your circumstances, you may want to investigate whether you'd qualify for Austudy if you're thinking of going back to full time study.
Your story has actually reminded me of a student story shared recently by one of our learning consultants, Adrian. It's quite inspiring, you might enjoy it: http://youtu.be/-J5A_Pvn_XQ
Good luck with your studies Hertzy and happy to help if you're after any further advice or support.