Your father should be able to release equity on his unencumbered property, by taking out a Buy to Let mortgage. Do some research on the Internet and go and talk to either your Bank or a broker (brokers may charge a fee for their services) and from information provided, decide which lender you want to go with. There are not that many lenders in the buy to let market now, so choice will be not be vast. There are likely to be some hefty fees and the maximum Loan to value will vary. Look carefully at the rates on offer, fees payable, tie in periods and what happens when your current rate expires. Most lenders have a criteria to fulfil, ie they mayrestrict the amount you can borrow, as usually the rent you can expect to achieve has to be 120% of an interest only payment at the chosen buy to let interest rate.