I've supported a friend through similar. Firstly, book an appointment as soon as possible. If you are very fearful, say so when booking. And for very anxious patients, this first appointment does not even need you to sit in the dentist chair or even let the dentist see your open mouth. A dentist experienced in phobia will be happy to sit and have a normal conversation with you about what she can likely do for you, and what might be anticipated for you, in terms of examinations, and possible treatments. If you are sitting eye-to-eye with the dentist in a regular chair, it's just a regular conversation and you can leave at any time. My friend's dentist told her that taking this approach, a number of nervous patients graduate to sitting in the chair or letting the dentist look in their mouth (without or even with instruments) at the first appointment. The dentist's aim over the first appointments (however many it takes) will be for you to undertake an exam, x-Rays, likely a cleaning session with a hygeniest also. And based on this, she will recommend a treatment plan for you. That way, you will know what you are dealing with. I know you are very fearful but i can really reassure you that the exam is not at all painful. It would be a huge step of you can set this as your initial goal and get yourself to that stage as soon as you feel comfortable. Even for non-phobic patients, the first appointment is usually the exam only and any treatment identified will come in a subsequent visit.
Secondly, modern dentistry has very little pain. Assuming you are not in your early 20s, and assuming you don't walk in with a mouth full of infected accesses (you didn't mention being currently in pain), you can banish any previous painful experiences as wildly outdated. Dentists nowadays work very hard to avoid pain and to minimise discomfort.
Thirdly, a huge range of problems are solvable without extracting teeth. You might need extractions but there is a really good chance that you might not. There really is only one way to know - book that appointment.
Finally, don't worry about being lectured to or scolded. Modern dentists are all about looking forward, supporting you to achieve and maintain good dental healthy now on. They are not going to shout or tut at you, regardless of the condition of your teeth. And chances are, whatever you have, the have seen it plenty of times before.
It helps if you really thing about what your fears actually are and express them to the dentist. If you prefer, you can send this by email or hand it over in writing during the appointment. Is it the noises of the unfamiliar machinery that frightens you, or laying back feeling vulnerable in the chair, or the prospect of pain, or embarrassment? Or all of the above, or something else entirely? The more you can identify and 'own' your fears, the better you can communicate with your dentist and work together to overcome them, or at least to sidestep them.
I will say though that having money to arrange for private appointments is a big help. Dentistry isn't cheap but it is so important for you. You have made a big step in asking for help. Now go for it. I have never heard of anyone in your position regretting it; everyone says they wish they did it years earlier.