It is possible as I did this.
You need a healthy deposit[20%]and your IVA must be upto date.You will need permission of your IP and the mortgage payments must not impact on your ability to pay your IVA payments
We have the deposit and mortgage sorted. Had a letter from IP saying mortgages were viewed as credit and therefore I couldn't have one but was told before starting IVA that mortgages were fine as they were secured against house. Now my IP will not return any of my calls.