remember in france any serious and life threatening diseases and any stay in hospital over 4 weeks is paid for by the state.
not sure about dentists but in 10 years in the UK I never went to one, still got all my own teeth.
eye tests and glasses not sure about as well, but before I left the UK got glasses from Tesco for £15 a pair, over the eight years I have worn glasses my eye sight has not changed./
personally i would open a savings account and put a few euros into it a month just for emergencies.