I am 40 years old and have very bad teeth can I go in to hospital to have them all removed and if so how do I go about it

No, as you would need a Dentist to refer you.
Although your local hospital may well have a dental school where you will be able to get reduced/free consultations.

In some countries it is common, but in the US it would require referral from a doctor, because of other medical problems that need monitoring.