您好,房屋必须要到无法居住的状态。至于如何属于无法居住,这要根据case by case了。建议您和tenancy tribunal 直接申请取消合约。
59A Termination where breach renders premises uninhabitable
(1) This section applies if, as a result of a breach of the tenancy agreement (whether for a fixed-term tenancy or a periodic tenancy) by a party, the premises are destroyed or are so seriously damaged as to be uninhabitable.