For a British perspective, pretty much anything written by Rory Muir such as Britain and the Defeat of Napoleon, his two-volume Wellington biography, Gentlemen of Uncertain Fortune, or Salamanca 1812. The relevant sections of N. A. M. Rodger's The Command of the Ocean are a stimulating argument about Britain's naval war. Luke Reynold's Who Owned Waterloo? covers the postwar meaning of the capstone battle for Britain. Alexander Mikaberidze's The Napoleonic Wars is a global history of the wars.

In addition to u/kieslowskifan's recommendations (which I totally agree with, especially Mikaberidze), I'd add the following, depending on where your interest lies:

• Britain Against Napoleon: The Organisation of Victory, 1793–1815 - Roger Knight

• Guineas and Gunpowder: British Foreign Aid in the Wars with France, 1793–1815 - J.M. Sherwig(older, but still worthwhile)

• Britain and Wellington’s Army: Recruitment, Society and Tradition, 1807–15 - Kevin Linch

• All for the King's Shilling: The British Soldier under Wellington, 1808–14 - Edward Coss

• The British Soldier in the Peninsular War: Encounters with Spain and Portugal, 1808-1814 - Gavin Daly

• War, Public Opinion and Policy in Britain, France and the Netherlands, 1785-1815 - Graeme Callister (the author recently talked about the book on an episode of the Napoleonicist podcast, which is well worth a listen)

• No Want of Courage: The British Army in Flanders, 1793-1795 - Robin Thomas (anything from Helion Publishing's "From Reason to Revolution" series is really good)

• The Spanish Ulcer: A History of the Peninsular War - David Gates

• The Peninsular War: A New History - Charles Esdaile

The last two are the recommended histories of the Peninsular as they acknowledge the role that the Spanish played in the war, compared to the usual Anglo-centric accounts.