you basically need what is commonly called 'full comprehensive' cover on the contents and landlords liability cover.
shop around, as some companies will exclude theft, except by forcible and/or violent entry. This is to prevent you making a claim due to theft by tenant or one of his/her guests.
an added bonus woudl be if you could include loss of rental arising from an insured peril. This would pay you the lost rent if you could not rent due to some misfortune covered under wither the contents policy or the buildings policy, such as fire, flood etc.
You should contac the building insurers/broker as they migth be able to do a special dael for you.