The bank figure out whether you can afford it or not, the approx repayments would definitely have been mentioned but again not everyone takes in this info, it will all be on the loan offer when OP gets it.
OP, you will pay payments on whatever you draw down, easiest way to figure out how much it's going to cost is just ask bank for 'cost per 1,000' then you can figure out what any amount of a drawdown will cost approximately, there will be slight variations but it's a good guideline.