I'm with NFU and have just added puppy Louis when my renewal came up in August. For William and Louis together it was £362.77 in total, including a 10% loyalty discount. The policy provides lifetime cover, up to £4,000 vet's fees for each dog each year and the excess is £50.
I chose them when William was a puppy because one of my neighbours has 2 Cockers with ongoing, expensive health problems (one has immune system problems and is always at the vet's, poor boy, and the other has terrible problems with his joints) and NFU have always paid up. The 2 Cockers are now about 10 and 7 years old and both have had their problems for many years.
The only thing I didn't like about NFU was that they wouldn't pay when William was castrated because of an undescended testicle and I know that some other insurers will. But they've been great this year and have paid for William's MRI scan and all the physiotherapy he's had for his back problem.