I got lots of quotes last year when Henry was 3-4 months, and they varied from about £20 to £35 per month (I'm in London, which seemed to be 100% higher than same policy for outside London). I went with Axa as the premium seemed reasonable (but not too cheap) - £27 per month, and the excess not too excessive (£75). Also Axa had good reviews. How things change
I'm now with PetPlan - it's £32 per month, but obviously his pre-existing condition (cataract) is not covered (but I'm taking my case with Axa up with the Financial Ombudsman Service (FOS) so who knows what will happen).
Insurance is turning into a horrible business (at least for me!) - the whole point of a premium is to pay a monthly amount according on your personal risk (based on your dog's breed, age & your location) and if you don't claim you pay the premium anyway and don't get anything in return (apart from peace of mind) and if you do claim it should then pay off. Clearly with some insurers it doesn't work like this and there's no point in you insuring with them at all, as they end up just charging you premiums to match the expected claims (or more).
I now have some trust in PetPlan to honour the whole "lifetime" cover thing and not screwing me over by increasing the premiums ludicrously, but really my trust is probably misplaced - maybe they'll increase the claims in the second year massively. Any company could - in theory - do what Axa has done. Only time will tell if they get away with it (the FOS will respond to me within the next 6 weeks...)