The upcoming aniversary and last years film (now on DVD and available in Tesco for a tenner - other retailers may have it!) has resulted in a number of good books on the subject. Personally, I don’t think that the film gives the best impression of what happened.
The most comprehensive is titled “The Casualties of Peterloo” by Bush. It isn’t the most recent but, apart from describing the day’s events, it forensically examines the available information for every known casualty. In consequence, this will give you a good idea of where they came from and what they did for a living. Admittedly, the 600 or so casualties are not a particularly big sample of the tens of thousands who attended but it’s likely that this is the most accurate you’ll get.
The most recent I’ve read is “Peterloo - Voices, Sabres & Silence” by Graham Phythian which I wold recommend.