Thanks for the replies everyone..

We are looking at moving to live closer to family so would have to pay $350-$400 a week in rent anyway.. thats where my confusion begins  

I figure that if we can afford to pay it in rent shouldnt that also mean we could afford it as a mortgage repayment.. especially as we would be effectively paying $100 – 150K deposit (with our equity).. or doesnt it work like that?
We only have our current mortgage ($250K) plus a car loan ($8K) and zero credit card debt.. so we dont have excessive outgoings..

Sorry if i sound like a bit of a dumbo, I just dont want to bother going to a broker and wasting their time if theres no chance of us being able to do anything anyway..

Thanks again for your advice