The official receiver will have pass the property to the Regional Trustee Liquidation Unit or a Trustee. The trustee will then apply to the Land Registry and place a restriction on the property. This ensures that the Trustee receives 50% of the beneficial interest if the property is sold.
So I think in your case the only way the ex will be able to get your portion of the house, would be to purchase the beneficial interest from the Trustee.