When you are bored

Merlin:

You and Merlin would practice magic. You didn't know too much, but he taught you. In secret of course, practicing on small objects that could easily go unnoticed. 

Mordred:

He would take you to the woods and show you an old druid ruin. The King wasn't too happy about you visiting an old magical place with a knight, but he accepted it. 

Arthur:

He would teach you sword and other weapons skills. He liked to think that women didn't need to know those skills, but he wanted you to be prepared.