JNO, dentistrty needs a lot of improvement I agree, although here we seem ok.
GPs are different I remember my old practice in the 90s you needed a letter from the holy ghost to get an appointment but the surgery I'm in now I can usually be seen the same day or at worst the next day.
I can only speak as I find, I cannot answer for your experiences my experiences of the NHS have varied over the years (I got a hospital acquired infection in 1973) my father and mother etc. have all had good experiences on the NHS recently.
I personally felt/feel that the timescale for my appointments are reasonable.