Although landlords are not required to have landlord's insurance by law, you will probably find that it's more cost effective to pay out for cover for your rental property than for the repairs to your house should it be damaged or destroyed.
If you have a buy-to-let mortgage on the property then your mortgage lender may insist that the building be insured in the case of a fire or malicious damage, which is included in the Landlord's Insurance. They may also ask that the house be only let to professional tenants.
These days, landlord insurance policies cover everything from a tenant refusing to leave to having to pay to re-house them after a fire, someone dying due to loose roof tiles, or damage caused by a tenant (but always check your policy with your insurance provider).
Many landlord insurance policies also cover any loss of rental income due to a fire in the property, that is the rent you lost while rebuilding goes on and the cost of re-housing the tenant.
You should also make sure that you're landlord's insurance includes legal protection. This covers the landlords for loss of rent if a tenant refuses to pay and can also cover the legal bills incurred from getting the tenant out.
Whichever insurance package you agree to, every landlord's policy should include property owner's liability, which will cover anything that happens to your tenant - even as a result of your negligence.
Don't forget to let the insurance company know when a tenant moves in. If they are not informed that someone is living there when things go wrong, the insurance company may refuse to pay out on your insurance policy in full.