In reply to James Malloch:
The main reason for travel insurance is to cover you for any medical attention you might need which can cost 1000s but if you are a british national, medical treatment is free as is rescue so there's no need for travel insurance in that respect. Being a BMC member automatically covers you for 3rd party liability for say if you drop a rock on someone's head and they decide to sue you. As for possessions, these are usually covered under most house contents insurance.