You need to apply to the Court for a Charging Order, but you can only do this is you have obtained a judgment against your debtor (and, of course, they haven't paid you the sum due under that judgment). A Charging Order does not require the chargee to sell their property, but it does mean you have some security that your debt will be repaid out of the proceeds of the sale once the property comes to be sold. If you are successful in obtaining a charge, it will rank below any other charges already registered against the property (eg, by the debtor's mortgage company or any other creditors who have successfuly obtained an order).