How would you feel if someone owed you money and declared bankruptcy because they didn't have the guts to work hard and repay it?

Shoot me for saying it but I think that declaring bankruptcy in your situation is a total cop out and really really selfish.

You will have trouble getting a mortgage, renting, buying goods on payment plans, getting a loan for a car, getting some jobs, connecting to services like electricity and home phone. Don't just think about what you are doing now - imagine where you want to be in 5 years time and ask yourself if you will have wanted to do any of those things. Declaring bankruptcy is a major step and not to be entered into lightly. It also sounds to me like it won't actually solve the problem - your DP clearly has money management issues. Lifeline offers financial counselling and so do other organisations - I think that it would be a really really good idea if he went to something like that.

Here are some other options (taking into account that I don't know your exact circumstances so some may not be relevant:
Contact everyone you own money to and work out payment plans with them.
You can get a new job
He can get a second job
Cancel your mobile phone plans and go to prepaid (and only use it in emergencies)
Move into cheaper accomodation - a single room in a share house is cheaper than living just the two of you - or move in with relatives
Make you lunch before you go to work every day rather than buying it (a loaf of bread and block of cheese and 5 apples cost $5 for a week rather than double that every day)
sell your car and catch public transport (although I know this can be hard in some parts of Canberra)
Go trough your wardrobe and sell 10 items each on ebay
Cancel your pay TV
Stop buying grog
Don't go to the movies - stay home and watch whatever is on
Every time you go to spend money on anything, ask yourself if you really need it

Also, I don't want to sound and harsher that I already have - but if you are having trouble managing your finances now I am not sure that you should be thinking about TTCing. I really think that this is something that you have to sort out and put behind you before you start thinking about having children.

I really do wish you luck - money troubles in never easy - what makes the difference is how you respond to them.