I've found his Baghdad Airport report that people are talking about:

http://news.bbc.co.uk/media/video/39050000/rm/_39050039_iraq_gilligan_vi.ram

In the report he never claims to have made it to the airport itself, he was turned away by the Iraqis on the approach road. There seem to be plenty of web pages having a go at Gilligan, saying that he claimed to go to the airport and the Iraqis were in control of it. This does not seem to be borne out by the content of his report, in which he states that he does not know whether the Americans are at the airport or not.