It is your responsibility to get the sum insured right. Ask for help if you need it. Ask about any choice of policy and the cost. This is the first part of any claim you might make which you have to meet yourself. The level of the excess varies according to which part of the policy you are claiming on, but is usually between 50 and 100, unless you are making a claim for subsidence, in which case it will be much higher, typically 1,500.
Insurance is designed to cover the cost of unexpected and unforeseeable losses.
It does not cover wear and tear. If your property is not in a good state of repair, your claim may not be met in full. You should be made aware of any limits or restrictions which apply if the building is to remain unoccupied for any length of time such as over 30 days. Yes, if you own a house. Your lender will usually insist you have insurance in place.