Unless the court has ordered otherwise, you do have a financial interest in the property by virtue of the fact that it is the marital home. Regardless, this should be disclosed to the IVA supervisor because it needs to be taken into account.
The fact remains that you have a legal interest in the house and it should have been disclosed.
If you have to go bankrupt, the trustee in bankruptcy would want your share of the house whatever it is. It may not be 50% of the equity, it may only be a tiny percent of the equity bought nonetheless, the trustee will want it.
If you go bankrupt, it wipes out all your debts but also takes any equity in the house which belongs to you.
It’s unlikely in the extreme that with a house of this value in this mortgage, that the trustee in bankruptcy would force a sale of the property even if you owned 50% of the equity. The trustee in bankruptcy and the courts will simply not force a wife out of the house particularly if there are children, unless there is a fantastic amount of equity in your favour which clearly there is not.
However I emphasise once again, this equity in the house, regardless of how much it is, should be disclosed.