Hi
Answers to your questions.
I'll answer 2 1st.
£156000 mortgage on repayment, £175000 on interest only. These would be 95% mortgages, I'm not sure without checking if you'd 100%, although the lender in question does do 100% mortgages so it's possible.
So, then moving onto question 1 - you could take the mortgage on interest only to start with and convert to repayment after you qualify.
Those are my best ideas. There are other lenders who operate with this level of generosity, but I've only checked the one to get an initial indication. They do take into account outgoings for loans and credit cards which you've not mentioned, so bear that in mind.
Hope that all helps
Adrian