Petplan for the older bunnies. Erin's is £237 a year but the excess is £110 + 20%. I've kept Erin's insurance going as she has regular dentals. (She's aged 9)
I've cancelled Esme and Tinkerbell's insurance, which were similar to Erin's as the monthly premium was ridiculous when I considered the excess and how likely I was to claim/how much I'd get back after the whooping excess etc.
Rudy is a tad older than them, (9 going on 10) and his insurance strangely is only £159 per year (also Petplan)
I have Dinky insured with Pets at Home (policy as it stood no longer available). She is now 9 and premium is about £125 with £75 excess + 10%. I will be keeping that on as long as it doesn't go as steep at the PP ones.
I won't be taking any more bunnies on for a considerable amount of time given that I don't feel confident with the insurance cover for older bunnies, but that's as I own many bunnies, for the odd one or two I'd just grit my teeth and do it.