While not a second-hand store, Waterstones does offer perks for students. If you sign up for a StudentPlus Waterstones Card, you can snag yourself a fresh copy of a book with 5% off your purchase.
For almost a quarter-century, I worked on the seminal, gigantic Computer Shopper magazine (and later, its digital counterpart), aka the phone book for PC buyers, and the nemesis of every postal ...