It is unlikely that you will need to make an offer for the house due to the small amount of equity. I take it that your Ex owns a 50% share of the house so your equity will be £1,000. I would suggest that you will be asked by the OR whether you wish to buy back your interest in the property for a nominal £1 plus £225 legal costs.
Once the OR has a valuation of the property, and confirmation of the mortgages and charges registered against it they will be able to agree an amount to settle their interest in the property.
This will have to involve your ex partner if he has an interest in the equity but isn't bankrupt
If your ex partner no longer lives with you, but is a joint owner, the OR will assume that they will be liable for half of the mortgage when calculating any income payment agreement - but it would depend on their circumstances as well as yours