Otherwise known as general liability insurance, will protect against claims arising from injury or property damage of persons other than your employees. Most businesses will have some level of interaction, either by you visting their premises or them visting your premises. If you work from and don't interect in person you have a very limited exposure. However, it is usually recommend that all businesses buy public liability insurance in csase they do and an accident occurs. For £80 annually, it's not worth taking the risk of not having the cover in force.