score:8
It would depend on the security officer that checks you in and the country where your flight originates.
TSA doesn't allow frying pans especially cast iron ones it's check only as evidenced in a blog from Forbes.
TSA also has a mobile app now that you can look at. But since it's a flight originating from another country TSA rules may not apply so originating country's rules will have to be followed.
Based on additional information
There is nothing specific regarding skillets for carry-on luggage in the UK so they may allow skillet through but I would still put it into a checked bag or just ship it home.