Well, after a lot of looking I've got an answer - of sorts - so, for anyone who's interested.....
I'm still not quite clear as to what Adobe product supports editing of AVCHD natively. I have found that Pinnacle Ultimate 12 does, and very well too, however to edit a full resolution AVCHD file will require hardware with at least quad processors, so my kit is not up to it.
Oddly enough, Windows Media Player 11 will play it very well, and I have found a nice little application (very cheap) called VoltaicHD which enables me to re-encode these files to WMV or AVI which virtually any video editting suite can handle with no problem.
Seeing as I am going to be playing these clips on non-HD TVs, giving them to rellies on DVD and playing them on my computer, this setup will do me fine. The files look very good in playback even after re-encoding. In the future when I have higher-spec kit and Adobe finally get their finger out, native editting may be possible.
If anyone has any better info, could you let me know?