I can only comment on my own experience. I have my dogs insured through M&S for around £14 per dog per month.
For this I get whole life (very important) cover & £7k cover (youd be amazed how quick vets bills mount) per condition per year.
The acid test for any insurance policy is how they deal with your claim. I have a young lab dog that needed a hip replacement which was diagnosed after I had made only a couple of payments. The total bill came to around £4.5k which M&S paid out no problem (barring £70.00 excess).
Thoroughly recommend M&S
PS in my experience most vets push (very expensive) Pet Plan policies but cannot find any difference to any other reputable company (apart from the handsome kick back the vet recieves
You are wrong about vets receiving a kick back from insurance companies. They are not allowed to give advice on which policies to take out, it is up to the client to choose which suites him ( the client ). Insured clients make a lot extra paperwork for which vets don't charge. If you have a specific case with definite facts, not opinion, pm me and I will take it up with the Royal College and the FSA
Sincere apologies if I've posted an untruth regarding vets receiving kick backs. My own vet seems to push one insurance company to the exculsion of all others (most of whom offer exactly the same policy for much less) which is why I assumed that vets received a comission.