@EssPee, hi, one of those lectures was
"Guerilla Warfare, Ireland 1920-1921", a post-war lecture given by Major (later Lieutenant General) A. E. Percival.
Reprinted as Chapter 8 in 'British Voices From the Irish War of Independence', ed. William Sheehan (2005)
The Britain's official 'Record of the Rebellion in Ireland 1920-22' contains training/instruction documents that were drawn up during the conflict.
E.g. "Appendix X – 5th Division Standing Orders for Armed Parties moving by Lorry, and for Lorry Convoy".
The start of "Appendix XXIV – Notes on Guerilla Warfare in Ireland" refers to 'tactical exercises carried out at guerilla warfare classes held at the Curragh'. The latter was a major British Army base in Ireland.
Its possible these classes took place during the truce that preceded the Anglo-Irish Treaty in December 1921, as hostilities were expected to resume if and when negoiations failed.
Part of the Record has been printed as 'Hearts & Mines: The British 5th Division, Ireland, 1920-21', ed. William Sheehan (2009).
Another part of the Record has been printed in 'British Intelligence in Ireland 1920-21' ed. Peter Hart (2002), from the Jeudwine papers held in the Imperial War Museum.
Hope this is of use.