How much equity do i need to borrow against and how do i find this out?

If you want to refinance your present mortgage, you should have 10% equity in the property. You should first contact your lender and get to know the amount of debt you owe to him. Then you can contact an appraiser and check out the present value of the property. You need to subtract the amount that you owe on the property from the property value to know the equity.