I think we all need to know a bit more before we can comment, let alone help. Did the CAA at Gatwick reject your application on these grounds or did they refer you for an assessment with someone else, a CFI (which would seem a little strange as that does not always mean a Flight Examiner) or a Radio Examiner perhaps? How does NATS fit into the story? Give us all the facts in detail and a flood of opinions and advice will follow, all of which you should sift very carefully!