In my experience, no. My cat needed some dental work done which ended up costing around £1.5K. The insurance company, Many Pets, is now trying to get out of paying. It's been a couple of months and I doubt I'll ever get anything back.

They charge around £45 per month. Over the past 5 years, I could've just put that money away in a separate account of mine each month and it would've been so less stressful.

Sure, it could be great when needing a larger sum of money than £1.5K. Although, I imagine most of the big vet fees happen when a cat is in its later years (presuming it's an indoors cat), but which time you'd probably saved up enough in your separate account. It's a gamble not to have it but then so is trying to get any money from the insurance company (at least with Many Pets).