I had Fern insured with Healthy Pets Gold option and they paid out without any quibbling, with the exception of dentistry as you say. She had an abcess under the tooth and the tooth had to be removed. They wouldn't pay for that.
The £5,000 is per condition over the pets lifetime. So is your dog has several different conditions, then each one starts at zero£ up to £5,000 maximum, with no limit on the number of conditions. Fern had a few grass seeds removed under GA, but each grass seed was treated as different condition, as it was caused by a different grass seed. It never would have reached £5,000 anyway.
Her last few days cost over £2,500, but she'd never had any pancreatic condition before, so the money clock was set to zero when I took her in. They have paid the vet direct without any problems.
Bella is now insured with them. As she has only just turned 5, her premiums are about half that I was paying for Fern, who was 10.
My previous dog was insured with Tesco, who have a time limit of one year for any condition. When she developed arthritis I had to pay for all her treatment related to arthritis after the first twnelve months. I would never insure a dog again with a time limit on a condition.