My macbook pro is typing # instead of UK pounds sign

Sounds like it's configured for a US keyboard, not a UK one.

Check System Settings -> Language & Region and make sure English (UK) is set as your preferred language.

You can also check System Settings -> Keyboard -> Text Input to make sure your keyboard is set to UK, rather than US

Make sure the only item you have on the list at system settings / keyboard / text input / edit / all input sources is named “British”. Use the + and - at the bottom of the list to modify.