Are you 'joint tenants' or 'tenants in common'. If in doubt (and you've not got the relevant paperwork to refer to) download a copy of the title register from the Land Registry's website. (It will cost you £4):
https://www.landregis...ortal/Property_Search
If you're joint tenants neither of you owns a specific share in the property. (It's your legal partnership which owns the whole property). Therefore neither of you can sell your share of the property (since such a share does not exist), nor force the sale of the other person's (non-existent) share. You need to change your ownership of the property to 'tenants in common', whereby each of you owns a specific share of the property. (Usually 50%). Speak to the Land Registry about changing the type of ownership. (Your former partner has no right to object to the change). Phone 0844 892 1111 (M-F, 0800-1800) or email
[email protected].
If you're tenants in common you can then seek a court order for the sale of the property. It's theoretically possible to do so yourself but I'd strongly advise using a solicitor.
Chris