I don't want to be a downer hun, but I think you might have a way to go yet. You also need to factor in legal costs which add up, and of course moving expenses. At best you could probably borrow 95% of the value of the house, but 90% or less is preferred and of course under 85% you don't get hit with mortgage insurance. If you are looking at 95%, 5% of $300 0000 is $15000 plus you will need to come up with at least enough extra to cover legals, stamp duty, pro-rata rates, moving expenses, costs for things like pest and building inspections, building insurance, preferably contents insurance, and you do usually need to make your first repayment in advance. So I would say at least $30 000 to make sure you have enough. Plus the lender will want at least one of you to have a stable, secure job, and you will need to demonstrate a savings history. Even if you were lent $30 000 it is unlikely that you would have a mortgage approved without being able to show your ability to put money aside each month.

Is renting from someone else for a while an option? Or could you ask your MIL if you can go on a rental contract like you weren't family, so that she is liable for the cost of repairs that are not your fault?