I highly recommend skipping this airport if at all possible. I have traveled around the world and recently found this airport very scary. I was there 3 days over the last 10 days during stops in transit and here is what I experienced (mind you one stop was prior to the fog related problems which only added to the horror):
1. Most long lines are at the FRONT of the airport at check in and the beginning. When you start to recoginize the amount of people before you even get through the NUMEROUS security check points, you realize you are more in danger on the front side rather than the back side.
2. The lines or ques move very slow due to severe understaffing at airline counters and security.
3. Once through security (who we found more rude and frightening than any other employees we experienced at Heathrow) in Terminal 3 - the international terminal, you are farmed into one main area holding point. They do not give out the gate numbers until your plane boards - so you are sitting with 10 to 20 + other flights waiting for your gate number. Again - not really understanding the safety in this other than you have to get through security to get there. With thousands of people in one place - it just didnt seem right.
4. If you see news of delays becausce of fog or whatever - DONT GO. They will put you in a tent outside with thousands of other people all waiting for their flights too. NOT SAFE people.
Heathrow should be a prime example to many other international airports of what NOT to do. There own security defeats the purpose of safety from terrorism. Terrorist dont need to get on the plane when they have access to thousands of people waiting to get through security and other long lines for check in and ticketing.