In reply to LastBoyScout:
> wondered what people use before I just go and sign up to British Cycling membership.
You may already be aware, but just in case, British Cycling membership only provides third party cover. I.e you're covered for damage you cause to other people and/or their property, but your own bike is not covered.
I'm insured through Cycleguard, who give me a discount for my British Cycling membership. But I've never claimed with them, so can't give you any info on how good or bad they are.