Afternoon Em/Mark, and welcome to WAB!
It's nice to hear they're interested! Tell them when you see the flakes (
like it! 
) next time, they are probably so-called
Ant Woodlice - known as
Platyarthrus hoffmannseggi scientifically, and live happily alongside their ant-hosts. These aren't seen all the time given their habitat of hiding in tunnels that are so often built under slabs or obsctructed in some other way.
Here's one I saw earlier this year - the first time I had in years, and probably only my second or third sighting ever:
2010
Ant Woodlouse, Platyarthrus hoffmannseggi One with the ant Lasius mixtus, and then in a specimen pot
Despite being quite descrete insects, they are widespread enough - just hard to track down!
Take care,
Jason