I live in forlorn hope of finding a Waterloo veteran in my family. My gggrandfather 1792 to 1857 would have had to face the ballot about 1808. I know nothing about him until he married in Newland, Glos. 1825. There is a man, same name from Dixton-Newton who joined the Monmouthshire Militia in 1809, transferred to the 56th Regiment in 1813. Have to check whether the 56th was at Waterloo (wasn't).
Still, an elder brother 1785 to 1848 joined the 90th Perthshire Volunteers (Light Infantry) and went to the West Indies in 1805. Took part in the capture of Martinique and Guadeloupe from the French. This is after Villeneuve sailed to the West Indies to draw Nelson away from the Channel (Where was the Channel Fleet and the North Sea Fleet?). He was in Canada during the war of 1812 against the U.S. Discharged due to ill health 1818.
This para from a genealogist employed by a cousin to take my researches back further. Only less than a generation due to date PR's commenced.
Added: 3rd Battalion, formed 1813 was in Holland in 1814 but not at Waterloo. Possibly part of the blocking force at Hal (10,000 men), in case we needed to do a runner if Boney got lucky.