There are two organisations in the UK which have formal arrangements with airlines for discounted travel for ATCOs.
One is a professional organisation which represents ATCOs interests and the discounts are part of the benifits available, the other organisation is dedicated solely to obtaining discounted travel and other associated benefits.
I used the latter extensively when I was younger and it was rare to be bumped off, if you were there was a lot more flexibility in the industry which allowed discretion by the local airline representive - sometimes travelling via a different airline for no extra cost or even first class on two long haul flights
.
There are still some good deals to be had, but as has been pointed out the flight only deals are almost always standby travel, you've got to be flexible and they're not suitable for family travel or if you have a specific deadline to meet.
If you are travelling on a long haul flight, there's nothing wrong with dressing smartly, subtley mention at check in that you work in the industry and ask if there's any chance of an upgrade.
