What Air born says about the 3 tests is correct, however I diasagree with the comment on salbutamol not being approved. I have salbutamol and the doctors didn't question it at all. I even asked about what was acceptable and was told it was fine.
I ran round the car park for 6 minutes because the treadmill was busy, there were no noticable fumes from the departing aircraft. If anything there is more from the cars entering the car park so I wouldn't worry about avgas fumes.
The cold air trigger may be your biggest problem. The best thing for you to do is ring Gatwick and speak to an aeromedical advisor. They were very helpful and tell you exactly what you can and cannot use.
Good luck.
NH