Donlon Books is an atmospheric little bookstore on Broadway Market (in East London.) They sell rare art books, style publications, and homemade photography zines.
In between soho and covent garden. There ares lots of great independent shops on this street. Dover bookshop, magma, super superficial and Mint to name a few. Also if you want a cheap lunch on your work break Cafe No.1 is amazing. £2.50 jacket potatoes with cheese and beans.