As has been said - the CT is normal. It was presumably to look for a bleed from the head injury and there was none
So the question was what was the injury? - if you were playing rugby and lost consciousness for a few seconds, no problem. If you had major injuries in a road traffic accident, or had prolonged loss of consciousness, or have had post head injusy personality chaanges Gatwick may be more interested
As has been said time and time again, iit is VITAL to ensure your doctor doesnt write something that risks your licesne simply from ignorance - putting down that your loss of consciosuness was more than a few seconds and you then had secondary amnesia was totally unecessary for the CT request. It may or may not have been accurate (you presumably couldnt have told him that as you were pieballed!!!!!) but sadly it is on your record.
Telling Gatwick fibs is naughty. Stopping your doctor speculating is good advice