There are literally tons of Napoleonic War resources, of all levels of detail and scarcity since many are no longer in print. Here are some of my favorites. Perhaps the best single volume English text is The
Campaigns of Napoleon by David Chandler. It is rather large and suffers from a lack of good maps but it is a classic and highly recommended if you can find it at a reduced price. A lower cost option would be
The Napoleonic Wars by Barnes and Fisher, which is compilation of Osprey’s two part survey of the Wars. For the Peninsula side of the Wars, I would suggest The
Spanish Onion by David Gates or the
Wellington in the Peninsula by Jac Weller. Both are readily available in excellent used condition and quite good. For Napoleonic tactics and a soldier’s view of battles, the two best I have found are
Tactics and the Experience of Battle in the Napoleonic Age by Roy Muir and
With Musket, Cannon and Sword by Brent Nosworthy. Of course for Waterloo, there is also the most excellent
The Battle by Allesandro Barbero.
Other excellent Napoleonic War texts which may be a bit beyond your general interest included
The Napoleonic Data Book by Dingby Smith, a short detailed summary of every battle of the period.
The Waterloo Companion by Mark Adkin
A Military History and Atlas of the Napoleonic Wars by V. J. Esposito
Interestingly you can also find a great deal about the battles and units involved from various web sites like
http://www.napoleonguide.com/battle.htm
http://web2.iadfw.net/napoleon/
I would especially recommend the excellent
Napoleon Series web site which has a wealth of information on just about everything on the period, including the battles and campaigns and a very scholarly set of forums on various topics.
http://www.napoleon-series.org/
) Just to give me some ideas for dios and where the units were and who they battled against etc.... 
