Hello Jon
Welcome to Poms in Oz.
Unless you and your girlfriend are eligible for Working Holiday Maker Visas, "very soon" and "DIAC" tend to be mutually exclusive ideas, my friend!
How old are you both and what does each of you do, please?
Also, what do you want? Do you want to go to Oz for a couple of years, travel around, see what you think of the place and then, in all probablilty, come back to the UK for some serious saving and some serious honing of skills in order to plan for a permanent move at some future date?
I think that if you want to retain the possibility of a permanent move to Oz "reasonably soon" then one neds to be a bit careful with WHM visas. It would be important not to disturb the chain of recent, relevant work experience that is required for skilled independent migration, I reckon.
I think your best bet would probably be to have a chat with a couple of firms of Registered Migration Agents fairly promptly. The good firms do not charge for 10 minutes or so on the phone and they can cover a LOT of ground with you in that time. I tend to suggest chatting with someone from Go Matilda and someone else from Ian Harrop & Associates.
Go Matilda - Your Gateway to Australia - Visa, Tax, and Financial Planning for Australia
Registered Australian Migration Agents, UK - Ian Harrop and Associates
If you are both under 31 and have no dependent children then the quick, cheap way to go to Oz is as Working Holiday Makers:
Visa Options - Working Holiday Makers - Visas & Immigration
You can do the application on-line via the link above, it is cheap and the processing is very quick.
Permanent migration is an involved, fiddly and expensive process. The first thing is to see whether your occupations fit into one of the categories on this list:
A-Z Occupations List - Australian Skills Recognition Information
If so then think carefully about the requirements for the skills assessment in the relevant field.
The best of the
PR visas is the skilled independent subclass 175 visa if you can get a poositve skills assessment and you can score at least 120 points. If not, there are plenty of other possibilities but start at the top and work downwards I would suggest:
Workers - Visas & Immigration
Information Booklets - Applications & Forms - Visas & Immigration
Best wishes
Gill