We have Petplan for Shaney and have always been very happy with them.They have always payed out promptly with no hassle. You have to bear in mind the age of your pet on taking out insurance ,also the area where you live is a big factor in the cost.For example when we lived in London our premiums were quite high . On moving to the sticks they were reduced considerably.
It's worth looking here for comparisons http://www.compare-pet-insurance.com/
I'm with sainbury's they are less expensive than petplan they cover up to 6.5k per year and they insure for life and have always been very good at paying out, but with them as with most insurers the policey takes effect 14 days after you take it out this is so you don't try to swindle the insurance companies
I'm with sainsburys who are extremely good value and good service - being students we've moved a lot in last year or so and they have kept the policy bang up to date unlike my home and car insurance which find a change of address v difficult to deal with!!
I have six animals to care for so do not have pet insurence, but i put away a small amount each month to pay for any treatment needed, most vets will always come to a arrangement reguarding payment if needed , four of my animals are from rescue centres and have different problems which insurence wont cover so this i found was the best way