I got my minis from my local co-op, but they are not on the shelves but behind the counter. They are also available from amazon so if all else fails try there.
Good luck in your search!
I have only just noticed your post sorry
There seems to be a shortage on the mini lozenges in a couple of different areas lately - apparently (if I have been informed correctly) it is to do with the manufacturers. I have been working lately across Lancashire and Liverpool and have experienced the same problem in both areas.
Have you tried any other products? Let me know how you are doing and I'll advise you the best I can