Thanks for the information - I have found the application form at:
http://ukhas.org.uk/_media/general:m...on_jan_05_.doc
I have come across so many Notams with weather balloon release - all year, all the time, and to be honest pretty much ignore them. I will certainly be as specific as I can, but we need decent VFR weather for the launch. It's part of a school project (my wife is a teacher).