Welcome of the forum!
About English classes: everybody recommends Ms. Adriana Crom (you can find her on FB), she lives in Palermo if I am not mistaken. She posts on BA Expats Hub, a group on FB.
About dentistry: here dental care is cheaper, but the quality is usually much lower than in the US/EU, so make sure you go to a reputable dentist. Plus, not many healthcare professionals speak fluent English, so this reduces your choice a little more. From what I read on this forum, top notch people who keeps update with state-of-the-art technology and techniques in their respective fields are not that much cheaper!
About your general impression on the forum: you are right!