Considering an exoplanet detection as an extreme case of eclipsing binary is reasonable (though not all detections require an eclipse), so that’s certainly within the VSS skill set, This will likely evolve to include extreme spectroscopy if any desire to detect an exoplanetary atmosphere is to be taken seriously, but that‘s possibly decades away even for professionals.
Exo-/astro-biology is an interesting area (and one I’ve studied recently), but I’m not sure that it fits well in any existing section. Nor am I convinced that BAA members would have much to contribute at the moment – unless they intend to participate in human factors research (which does fit under the subject heading).