I reckon with pet insurance you either don't bother or you go all the way, we have Pet Plan for two Basset Hounds because they are capable of eating just about anything and they can also get bad backs late in life. The bad news is that it is £35/month. The good news is that there is one excess of £70 per year, no matter how many claims you make.
We have two sisters from the same litter, Myrtle and Spot. Myrtle managed to trap her head in the electric gates at work and had to be rushed in but luckily no operation required. Spot has had four attacks of Hemorrhagic GastroEnteritis (the first one very nearly killed her) which has cost over £5000 in Vet's Bills so far - and can strike again at any time. they've also had a few other minor things but those were the two lowlights so far.
Pet Plan paid up without a quibble for everything. Premiums have not changed.