I find the doctors in San Pedro and Belize City to be very good. Not sure where Timmy is, but our experience has been excellent. BUPA insurance covers us here and abroad. The providers do not bill the insurance company for you, but BUPA assists in processing paperwork and you do get reimbursed if you are due money.
An office visit is affordable - from $30-50 Bz, and surgeries are also reasonable.
Think of Belize like a small town - if you need specialized care you may need to travel to a hospital that specializes in that area. Another popular location for medical care is Medrida, Mexico. There are excellent facilities there for more sophisticated treatments such as chemo, heart surgery etc.