Membership of the BTA automatically provides you with third party insurance cover.
This means that if you are involved in an accident whilst using your bicycle in which another person is injured or their property damaged, and they threaten to sue you, you are covered for claims of up to $2 million. In the event of a claim, the insurance company will pay the other party to compensate them for their injury or property damage, rather than you paying them out of you own pocket, although there is an excess of $500 for property damage claims.
This insurance does NOT cover you when participating in competitive events.
If you take out a family membership, family members living at the same address, including children under 18, are also covered by the policy provided you include their names on the membership application form.
If you seek more comprehensive cover for theft or accident damage, there are a number of options. The easiest and cheapest option, if you have an existing house and contents policy, is to check to see what cover it provides for bicycles. Our experience has been that there is considerable variation between policies with some specifically excluding bicycles. For others a small additional charge can significantly increase the level of cover provided.
If you require more comprehensive cover for travel and/or particularly expensive bike, then you are advised to seek a specialist cycle insurer such as Cyclecover or Velosure. Even with some of these insurers you can reduce your insurance costs by also using them to provide house and contents insurance with the bicycle cover . It all depends what you want.
I would recommend that the minimum bike insurance to hold is third party. Mind you in 30 years of commuting I have never had a reason to make a claim, and the only bike specific insurance I have held is that provided by my BTA membership.