Just thought I'd post a friendly/helpful warning to Londoners flying out of Gatwick.
DD and I went from central London by car yesterday (thinking it would be easier as we had several big/heavy cases), and were horrified as we watched the minutes tick away while we were crawled along in bumper to bumper traffic. There is major construction on the A23. The roadworks cause 2 lanes each way to go down to one, and then to only one lane for traffic going both ways. The tailbacks went on for miles and miles - and I'm not exaggerating. We went from thinking we'd have lots of time to shop duty free/grab a bite to eat, etc to almost missing our flight. There wasn't an empty seat on the plane, (and their had been quite a few empty seats when I called to confirm flights the night before) as all were filled with people who had missed earlier flights due to the roadworks (and a bad accident on the M25).
So - plan your trip to Gatwick carefully, and if at all possible, take the train....