I got insurance for my camera equipment through my homeowners policy. They just wrote a rider (add-on) to my current policy covering all my camera equipment. I started out with $5000 and that covers $5000 maximum per incident and $2000 maximum per piece of equipment. I can increase the total maximum whenever I want, but the $2000 max per piece of equipment is my insurance company's limit.
Through my homeowner's policy there was some limited coverage as it stood, but this rider covers all my equipment if it's damaged, stolen, lost, dropped, smashed, and/or dropped in the ocean never to be seen again.
All for $14 a year!! Not sure how it works in the UK, but that's what I got here in the US.