G-KEST
If you look at the SETP website,
www.setp.org , you'll see the membership criteria, I think. To get into the Society at Member grade generally you need to be a working professional test pilot, with a credible CV accounting for your exploits. Associate membership is less stringent in its requirements. That said, our conferences are generally open to non-members. Like the RAeS, expect to pay a bit more to attend the sessions if this is the case.
The European forum is an excellent exchange of information:and very sociable!
The joint SETP/SFTE conference is, I suspect, likely to be short of space if we have the usual contingent from the USA (numbers were down at SETP Euro in Paris this year, still due to the 9/11 and GW2 effects.) I'm not on the organising committtee, so don't take this as gospel, but I suspect that non members may be squeeezed out if they apply to attend at a late stage.
Keep an eye on the website for details and booking forms.
Hope you will be interested and able to attend.