Please click on the link and enter how much you wish to borrow, in "Mortgage Amount".
Then enter how many months you wish to borrow it over, ie, 25 years is 25 x 12 months = 300
Enter the current interest rate, and simply press calculate.
As a rough guide, an interest rate of approx 4.25% can be achieved for the first 6 months. After that you would revert to variable rates which are currently around 4.5%.