I'm in the states, specifically in Texas (because stores in the US can be very regional in scope), and we don't have a Poundland. (Or pounds sterling even!)
We do have Dollar Tree, Family Dollar, Dollar General, Big Lots, and Walmart. And maybe a couple of others that I'm missing.
I've been making weekly rounds of them picking up lots of Matchbox cars like the Coyote, The ARV (I found some in a "Prehistoric Five Pack" with some other vehicles) a Buffalo MRAP, an HEMTT, and some Swat Trucks. So far I haven't found any of those APCs, but the search continues.
I did find some VERY cheaply made plastic military trucks five to a package for a $1 that are closer to 20mm than 15mm and I'm going to harvest their wheels bury them in sand and glue, and melt them a little to use as terrain wrecks.