This isn't Apple Pay - try reading the article next time!
All Natwest have done is enable you to log in to the Natwest app using your fingerprint. In the same way the Amazon app lets you log in with your fingerprint.
You can not go in to a shop in the UK and use RFC payments with this. Worst case scenario, your phone would need to be unlocked when the thief gets it, and it has to remain unlocked while they clone your fingerprint. Then they run the app and spoof as you, getting access to your bank accounts!
Where they can either transfer money to existing payees, or arrange for a small amount of money to be available at a cashpoint if you enter a code...