You can see a good replication of the Lindisfarne Gospels in the small church on Lindisfarne, and there are no end of gift shops selling books on Celtic manuscript illumination. The island is populated by artists, fishermen, and other independent spirits, having expelled British autonomy in the last century by stoning the local policeman off the island. You will hear many interesting stories if you spend an evening at the bar in one of the pubs. These won't be hard to find, as there are more drinking holes per square mile on the island than anywhere in Britain. Must be an inheritance from the monks.
As for Edinburgh, maybe you will be able to combine your visit with the Edinburgh Book Festival (www.edbookfest.co.uk) which organises readings, discussions and exhibitions. Try wandering down the Grassmarket where you will find quaint bookstores and shops selling string, honey and cheese. You will then be near the Elephant House Cafe which I agree is worth a visit - after all, it now has a claim to fame as the place where J K Rowling wrote Harry Potter, because she couldn't afford to heat her flat. Another good stop for the travel weary is the building for the Scottish Poetry Library down the Royal Mile, which is one of the city's most exciting new architectural developments. As well as books, it has some great artworks on the wall inspired by its collections. Finally, the Fruitmarket Gallery by Waverley Station always has stimulating exhibitions, and the bookshop contains a good selection of artists books.
If you have good transport, I'd recommend a trip to Little Sparta, the creation of concrete poet and publisher Ian Hamilton Finlay (www.gardenvisit.com/g/lit6.htm or www.perlesvaus.easynet.co.uk/hippeis/gallery/little_sparta). It would be a shame to miss such a unique and visionary artist's work in its natural setting.
Hope you enjoy your trip,