In British English, cat is cat! Or are you asking for common names for a cat, or ways to call them to come?

Moggy

'Cat' is 'cat' in British English! Or are you asking about British pronunciation? If so, just go to any good online dictionary and click on the audio button marked GB or British English. You'll hear that the standard GB (RP) pronunciation is /kæt/, which is similar to the American pronunciation but shorter and less close to an 'e' sound.

Kitty! :)