Hi Kristie84,
Jervis Bay is a great dive location, the underwater life is abundent.
There are so many different dive spots, which range from beginner to advanced. There is a great Livaboard called Ocean Trek which is great for a week end trip. I hope this is of help.

Just to let you know there is an australian dive forum which would be better to ask these types of questions as there are not that many aussies on this site that I have found. the web site is http://www.diveoz.com.au/

I hope you have a good trip