I don’t (yet) use ASTAP but thanks for drawing it to my attention. I will take a look.
Russ Laher’s Aperture Photometry Tool, APT, is my tool of choice. Written by a professional at the ZTF for professionals and amateurs alike it does a very good job very easily. It produces CSV format output which is easy to convert to a BAA-VSS spreadsheet. A script to do just that is available from me on request.
APT is available from https://aperturephotometry.org/ and there’s a Wikipedia article at https://en.wikipedia.org/wiki/Aperture_Photometry_Tool
A particularly nice feature of APT is that the apertures can be elliptical, so tracking errors can be tolerated better than with purely circular apertures.
For plate solving I use a local installation of astrometry.net with the Gaia DR2 catalogue.