I have my three (Slipper, Badger & Blueberry) insured with Petplan, it's £10 per bunny per month, lifetime cover. I can't remember the excess of the top of my head, but I've not had to claim off them so far (touch wood).
Blackavar is going with Helpucover, fingers crossed, which is identical to Petplan, but £10 cheaper excess and a bit cheaper per month. I've been quoted about £7 per month for Blackavar, they're just checking his medical history with the vet before they confirm due to the care he needed when I first got him.