People have given you great suggestions above. I would also suggest that you ask around you (family, friend) if they know a "good" dentist. If so, I would then go to the surgery and talk to them face to face, explain your situation and they might be able to help you (payment plan)
Talking to people face to face is always better than over the phone. A friend of mine did that a while back as she needed major work done and her dentist (who she did not know prior to that but had been recommended) agreed to that. Don't assume that because they have never done this before (so they say), that it automatically mean they can not arrange this. I do hope you get sorted asap.