It's a members-only library but you might be granted access with a research request. The writer's room is great but there's a few special, hidden corners among the bookshelves to tuck yourself away in.
The Sackler Crossing is part of a route through the 120 hectares of Kew Gardens, designed by John Pawson in 2006. Set low to the surface of the lake, it seems to float across the water.