If you're in the area of Cromford or Matlock, you should take the time to go to Scathin Books. It is a bibliophiles heaven, thousands of new and second-hand book, plus a vegetarian cafe.
I did find the second-hand books a tad over priced, but there is a huge selection to choose from. Our itinerary was busy, so I couldn't spend as long as I wanted browsing, plan to spend a good couple of hours here.
