Hello ClintonBaptiste
I attended the flyer professional flight training show in Dublin last year, highly reccommended. I found the dress code to be fairly casual with the majority of people, including myself, wearing jeans and a shirt. Anything along the lines of this would be fine. Tracksuit however .. not reccommended. I suppose you are just looking to affirm to the flight schools/airlines that you are taking the exhibition seriously in trying to further your knowledge etc.
From what ive read I do believe Gestair will be their. Take a look at this link for other exhibitors.
http://www.flyer.co.uk/exhibitions/exhibitorlisting.php
My last piece of advice... ask lots and lots of questions. I went home from Dublin wishing I had asked more. Enjoy grilling them for information
Hope this helps
MB