Do you need landlord insurance is answered by three questions, and the answers take a minute. There is no statutory requirement, so the obligation comes from a lender, from a lease, or from an exposure you would rather not carry personally.
Is there a mortgage on it
If yes, the lender almost certainly requires buildings cover for full reinstatement, continuously, with its interest noted, and can insure the property itself and charge you if it lapses. That settles the buildings half of the question without any further thought.
Do you own the structure
On a house, yes, and it is your largest asset at the property. On a leasehold flat, usually not, because the freeholder insures it under the lease. That decides whether you are buying a full landlord policy or a flat landlord policy without a buildings section.
Could you pay an injury claim yourself
A tenant, a visitor or a passer by injured because of the property can claim, and the figure is decided by the injury rather than by the value of the house. Property owners liability is the cheapest section on the schedule and the only one whose absence can cost more than the property is worth.
Questions people ask about do you need landlord insurance
Is it a legal requirement?
No. Only employers liability is compulsory, and only if you employ anybody. Everything else comes from a mortgage, a lease or judgement.
What if I own the property outright?
Then nobody requires anything. Property owners liability is still the section worth having, because the exposure exists whether it is insured or not.
Can I just use my home insurance?
No. Household policies are written for owner occupied property and exclude letting, which usually leaves a let property uninsured in substance.