Using the UK Faster Payment System is absolutely free. 

It's a quick and easy way to send one-off payments at the touch of a button. In most cases the funds are  received almost immediately, however sometimes it may take a few hours for the transfer to complete. 

As Faster Payments are processed in a matter of seconds, once the money has left your account, it cannot be stopped or reversed. Please always make sure you are sending a Faster Payment to the right account.