Mallory do one every Weds afternoon for bikes, check out their website. Otherwise, its scour the track www or some track day companies/race orgs who advertise them. If you know a meet is coming up at a track, chnaces are there will be a ACU day sometime before it, although most seem to be to thse racing with that club that I've seen
Cheers, found some as soon as I looked where you suggested. Not sure I will be able to get too many test days other than those the day before each race but if I catch 'er in doors in a good mood you never know.