B&Q opened a warehouse style outlet a short time ago in Milton Keynes.
Tonight, I was surprised (and pleased) to find a small selection of brass, aluminium, steel(?), and plastic extrusions(?) in a small variety of forms including tube, rod, and bar, and possibly suitable for use in model engineering. (I'd been aware of their hardwood mouldings for some time, but finding brass in a clean condition was a pleasant surprise.)
HTH others wading through the lists collected at the various exhibitions...