When I need inspiration for mentor/training RP I like to look back at the vanilla warlock quests as well as the old world of warcraft RPG tabletop sourcebooks. While the RPG books are non-canon on the specific details, their content is still very much in the intended spirit of how lore, magic, and classes were meant to be portrayed in the setting of Azeroth. You can find the PDFs online!
If you are looking for other people with similar RP interests to get info or tips from, and do not wish to leave your current guild, I recommend applying to the Order of the Lamb as a non-guilded member which will give you access to our discord. You can find our forum post here on the forums.