We rent out a house we inherited. We have the best landlord insurance we could find, and its saved our bacon a few times. As a pp said, direct line landlord insurance. It covers off the top of my head, among other things:
Rent guarantee, for If the tenant doesn't pay their rent, and the related legal expenses to resolve that
Legal support for evictions provided they are done within the law
Malicious damage by tenants.
Damage caused by flooding, leaking pipes etc.
Temporary alternative accommodation for tenants if there is a major issue with the property.
All the usual building structural, fixtures and fittings stuff is covered.
Lock and key replacement.
Liability cover for tenants and people working at the property. If our tenants sue us for something, we have that cover to allow us to legally defend ourselves.
And the absolute best part of the policy is the emergency cover, we've used it for a boiler breakdown, an unexpected drain blockage, and something else I'm sure. They have a 24 hour cover and will send out an engineer usually the same day to try and fix whatever has broken down. That alone is worth the cost of the policy, for my peace of mind if nothing else. I know whatever the tenants have a problem with, I can get someone out to fix it. I take my responsibility to my tenants very seriously, if something goes wrong, they need it put right asap.
Imo, no one should be renting out a property without solid gold landlord cover, unless you have very deep pockets.