I've got an excellent book about the trial, execution and burial of Charles I. It's titled: "O Horrable Murder" by Robert B. Partridge. There is also the book titled: "The King's Revenge: Charles II and the Greatest Manhunt in British History" by Don Jordan and Michael Walsh. Not sure if this is available online for viewing, or if you've already been able to watch it, but this documentary series is also very good:
Charles I: Downfall of a King