Kevin
You would have to continue paying both the mortgage and the secured loan, as these are not settled as part of the IVA, if you don't pay them your house could be repossessed.
However, in determining how much you can afford to pay into the IVA, allowance will be given for paying your mortgage and secured loan in full, so you don't get into trouble with these lenders. You would, though be obliged to remortgage your house up to 85% of its value in the final year of the IVA. As currently it stands at around 65% mortgaged, so if house prices don't move and your mortgage/secured loan balances stay the same, then you'd need to release around £20K of equity in the final year to bring the secured debt up to 85% of the propertry's value. However, if property prices plunge as forecast, then it's possible you wouldn't have to remortgage at all in the final year.
How much unsecured debt do you have and how much do you think you could afford to pay per month into the IVA (allowing for mortgage/secured debt to be paid outside the IVA) ?