you will probably find depending on where you are there is not an "emergency dentist hospital" even if you did find an nhs emergency dentist, they would only do the emergency stuff, then expect you to find another dentist for the more routine stuff. i think your estimate of 100's is wrong - from what you are saying it's more likely to be 1000's.
First and foremost, you need to find an NHS dentist. To so this you can either call your local PALS service at your local pct. They keep lists of the nearest dentists accepting NHS patients. No matter what you need in one course of treatment, you will never (currently) pay more than �198. You will find the PALS number in your phonebook or on your pct website (if, for example you live in norfolk put "norfolk pct" into a search engine. Or you could go to NHS choices webpage, put in you postcode and click on dentists. Click on each individual dentist to see if they are accepting new nhs patients.
secondly, are you on a low income or income related benefits? If so you may be entitled to free nhs dental care any way. See here to check for entitlements
http://www.nhsbsa.nhs.uk/HealthCosts/1558.aspx
lastly, you might be able to find a dentist who offers sedation (injection in hand) for procedures. You are sort of awake but remember nothing. You cant drive afterwards. In my local town the sedation clinic is just called "the reading dental sedation clinic" You may have one where you are. In Reading if you get free nhs treatment, you can also get free sedation, otherwise you have to pay.
Good luck