If there is no equity in the property, then the likelihood of your wife being affected by an IVA now is remote. However, do remember that in an IVA your are not discharged from your debts until the end, so during this period if property prices increase and you continue to contribute towards the mortgage and running costs of the property, you may well develop a beneficial interest in the property.
This will not be a problem if your IVA continues as initially proposed, however if you default on your payments and this results in a bankruptcy, you may well find a Trustee claiming a share in the property. I have successfully brought a similar action as Trustee in bankruptcy against a solely owned property which was relatively easy. It might be sensible to have a chat with a solicitor beforehand, to see if you could protect your wife through a legal declaration of interest if you are at all worried.
Regards, Melanie Giles, Insolvency Practitioner