Cover for a property that has previously been affected by flooding or subsidence is likely to be provided by specialist insurers rather than in the general market. Insurance is particularly important if there is a mortgage lender to consider as they will want to ensure that your home is adequately covered.
Before any new insurer would be prepared to offer terms, they will want to know when the damage last occurred and any previous history, the repairs that were undertaken and the cost if known, and any preventative measures that have since been put in place either by yourself, the previous owner or local authority.
It is likely that there will be a higher policy excess applied to that section of the policy both on the buildings and contents sections.