I'd recommend everyone use the App. It's really good. I was able to see that day my flight was cancelled, so I drove. On the day in question aircraft were fuelled with crew sat on the craft waiting to go and the operation was very go minded that day. It was pretty late on before it became apparent that the North terminal operation had to be stopped. It was so unprecedented that LGW management have been before the select committee. That day was horrendous but I recommend you all get the app as the flight tracker is the best I've seen and the info you get is direct from the people who make the operational decisions, and not a middle man.