I'm not able to pass the phone validation regardless of the values that I enter. Are you able to register with the form? If so what are the values you are using? In all of my testing there is nothing that is limiting .co.uk email addresses.
Do you have a default version of the Registration Pack setup? If so have you tested with this one? The code that we produce in the Solution Packs and with UE will not prevent emails from being sent to .co.uk addresses.