Well here goes. I'm going to put forward 2 suggestions for a meeting at Thursley Common in Hampshire.
According to my book it is one of the premier sites for odonates in the South.
It supports 26 species.(Drool)
My suggestion is either the weekends of 16th/17th June or 23rd/24th June.
I'm trying to get a peak for emergence, which is a tough one as they all do it at different times
Please feel free to chuck your ideas in the pot-I'm a beginner myself.
Jules Wild-Woman