If you own the building you operate from, or if you've made alterations to a rented space to meet the specific requirements of your trade, you should seriously consider taking out buildings insurance. If you don't and the property suffers damage, for example as a result of fire, flood or storm, not only would you have to foot the bill to repair the damage, you might not be able to continue trading.
You should also remember that you need to make sure the premises are insured for their full rebuilding cost (including professional fees and the cost of site clearance) and not their market value. You may need expert advice to calculate the rebuilding cost, which often differs significantly from market value.
Direct Line for Business offers a number of insurance policies that include cover for the building or structure - for some policies this may not be standard and you may need to take it as optional cover. The policies vary, but generally cover 'all risks' (subject to exclusions) so you can expect to be covered in the event of: