Why can't I get NHS dental care? (UK)?

I've never had a filling and my teeth have always been in good condition. After I had my son I went to the dentist who told me pregnancy gave me a calcium deficiency and would need around 5 fillings. I had to move to Kent which is 5 hours from that dentist so I couldn't just 'pop' back. It has only been 7months since I've had my son but I've been declined NHS help for a dentist. They said I can only go private as they have no room for me apart from a 3year waiting list (which will not be free for me then, plus my teeth are starting to hurt already). I do not have that kind of money and I'm worried sick, does anyone have any advice?
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They only take a limited number of cases a year and since its so limited, dentist take more private patients, the NHS is also in shambles
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