Hi, my question

Hi, my question is regarding my front tooth. Ive been experiencing difficultly with it ever since I had a post crown. I’ve had 2 abscess like infections which as a result I changed dentists.
My new dentist referred me to an endodontist as it was out of his league.
So I’m now 6 months into my treatment for an implant. We agreed a set price for this, I’m paying this as you go. I’ve had roughly 3 treatments with this endodontist now. On my latest appointment, he assessed the healing of my root canal as I need a bone graft. But he needs a second opinion now as it isn’t healing as expected. He’s now referred me to a doctor for a second opinion. This he expected me to pay for which was not part of the original agreement. I explained this to the doctor, who was very understanding. He gave me some free advice, although I haven’t committed to the following treatment. He said that there is still infection, and will always be, unless I have it looked at. This will take a further year to heal. As you can imagine I’m deeply disappointed with the endodontist.
The doctor did however suggest that I could go through the nhs for this treatment.
So my question is, do I go down the nhs route? Maybe even for the implant also?
Thanks for reading