If you're interested in learning about 18th century London, I suggest starting with Liza Picard's Dr. Johnson's London. For more in-depth resources, or information on apothecaries and poisoning deaths in the 18th and 19th centuries, you may consider:
At Home with the Georgians. BBC. 2012. DVD.
(ed.) Beardsley, Martyn. Grateful to Providence: The Diary and Accounts of Matthew Flinders, Surgeon, Apothecary and Man-Midwife 1775-1802.
Downing, Sarah Jane. Beauty and Cosmetics 1550-1950.
Hart, Avril. Fashion in Detail: From the 17th and 18th Centuries.
(ed.) Humble, Nicola. Mrs. Beeton's Book of Household Management.
Inglis, Lucy. Georgian London: Into the Streets.
Phillips, Hugh. Mid-Georgian London.
Picard, Liza. Dr. Johnson's London: Everyday Life in London in the Mid 18th Century.
Porter, Roy. English Society in the Eighteenth Century.
Rocque, John. Map of Georgian London, 1746.
Sandling, Ted. London in Fragments: A Mudlark's Treasures.
Stewart, Amy. Wicked Plants: The Weed that Killed Lincoln's Mother & Other Botanical Atrocities.
Stratmann, Linda. The Secret Poisoner: A Century of Murder.
Smith, Charles Saumarez. Eighteenth-Century Decoration: Design and the Domestic Interior in England.
Thompson, C.J.S. The Mystery and Art of the Apothecary.
Vickery, Amanda. Behind Closed Doors: At Home in Georgian England.
Watson, Katherine. Poisoned Lives: English Poisoners and their Victims.
White, Jerry. London in the Eighteenth Century.
Yorke, Trevor. Georgian and Regency Houses Explained.