In case you are running low in budget then you can seek help from CARE CREDIT. Under this, the company pays all your expensed to the hospital or clinic and you can return them in free monthly installments. Else you can seek help from NHS.
Also there are dental schools where you will be treated by budding dentists but will be under strict supervision of experts. The cost there is very less or may be free depending upon the financial status of patient...for more info you can visit the link...http://www.identalhub.com/article_free-dental-care--496.aspx