Erm... what's an airsoft show? Don't know what you mean. 
You've got nothing to ein, zwei, drei, vier
There have been some displays possibly by CIA to encourage support at Beltring I think.
I try to encourage it also at shows I attend in my area.
That is about as close as I can think to what you may mean, as airsoft isn't a spectator activity but can be made into a nice video with some pre planning as long as it does not get in the way of the fun on the day.
Free speech is expensive these days!
CiA has never had a stand at shows but Gunman Airsoft has had a stand at Beltring for the past two or three years (along with major airsoft retailers).
There is an annual airsoft fair in the Birmingham area which has airsoft site/retailer stands and a glorified bring and buy market.
Beyond that I can't think of any 'mainstream' airsoft shows but then I probably wouldn't have noticed even if there were!
The next Airsoft Arms show is in May - http://www.airsoftarmsfair.com/
It's not specifically WW2 though.
If you want to look at repro uniforms then there is a militaria fair in January at Stoneleigh (near Coventry) where there will be many of the big suppliers of uniforms and accoutrements. Always best, if you can, to buy uniforms at shows, trying them on for fit.http://www.militariashows.com/
Most airsoft gun suppliers have shops so easy enough to view in person.
