Answer : Great question, so much you can do with that!
I would recommend enrolling in a university program in interior design. This is a great way to learn the skills needed as an interior designer and be able to earn your degree too. In Australia there are many options when it comes to universities but I think TAFE SA has one of the best programs (the government standard). I speak from experience since my husband works at TAFE SA where he studies coursework on Level 3 Diploma in Interior Design. Even if this course doesn't suit you there are many other courses for university degrees, specializations or higher diplomas for majoring in Interior Design. So take your time, explore and find out which option suits you.