The fee you pay is £250 (for example), but that may come nowhere near covering the full cost of the course of treatment. Dental treatment can be expensive.
I agree that dental work should be free or very low cost to the public. While the impact of having a missing front tooth might not be massive in terms of health, it can be significant cosmetically and that has real implications (confidence/mental health/workplace etc).
I tell you what else should be NHS/government funded… guide dogs. It’s an absolute disgrace that they’re not. I know a blind health economist who did a cost-effectiveness study in their own time to prove that it’s cost-effective.