There is no registration of names in the UK, and consequently there can be no on-line resource for finding names.
Your name is what you call yourself, and what other people call you. You can go by more than one name at the same time. You can change your name without any formality - all you have to do is start using your new name, and get other people to use it too.
The indexes to civil registrations of births, marriages, and deaths at England’s General Register Office begin in 1837 and go up to the present. They are available on microfiche at several archives and libraries: