We Americans often earlier church interiors to have been bare, unadorned wood or stone. That's part of our Puritain heritage, and also partly fed by the fact that medieval cathedrals today are usually bare stone. But the medieval church would have been brightly colored - polychromed - and the walls were often decorated with elaborate paintings of religious scenes. The Painted Church website (an older site full of useful material) collects, by topic, images of most of the extant wall paintings in medieval England.
As a follow-up to the fly-through of early seventeenth-century London, I suggest the Map of Early Modern London, hosted by the University of Victoria and based on the 1560 woodcut map known as the Agas Map. You can view the map image by image, click on designated links to learn more about the different London locales, use the Encyclopedia to locate specific places, read early modern texts that describe or talk about London, and more!
What would the streets of sixteenth- and seventeenth-century London looked like? What would you have seen as you walked through town? Shopfronts, vistas, church squares? How did vendors display their wares? What were the street surfaces like? Buildings? Wharves down on the river?