The only shop mentioned that I know is Target. Unfortunately, it's no longer worth visiting, having gone the same way as the others. Radio rallies seem to deal in junk, but it's the SAME junk. There's a klystron and power supply that has gone Harwell, Dunstable, Newbury, Frome, Wimborne, for three years now that I,ve seen, and an R1155 that I'm sure I first met at Woburn!
Perhaps there has been a period where junk was not reclaimable, but with the increasing use of flash memory in devices, and the availability of free software from manufacturers, its time may come again.
Harwell's only a couple of weeks. It's only five minutes away on foot.