Corneal Dermoid cost and reoccurrence possibility?

My mini smooth Dax was born with a corneal dermoid. I only noticed this the day after I brought him home from the breeder, when I took him to the vet to be Vaccinated and she pointed it out . I wear glasses for reading text and had not seen this the day before. I decided to keep him and not return him to the breeder as this felt a bit mean. But, was advised by the vets that surgery can be expensive, and he'd be referred to a specialist animal hospital in Ipswich. He is now one, so he's probably fully grown and ready for any op needed. He was insured when I bought him, and I continued the insurance with the same company Pet Plan, so I'm hoping they will pay

Does anyone have any experience of this? Cost and recovery, or whether it can reoccur?

Thanks