Oh, so that's where I recognised her from possibly.
Eggs, if you watch any of Merlin you won't want to see every episode. The makers based it on Smallville to quite an extent, and it's formulaic in exactly the same way. Instead of "oh, there's a new person at school and guess what, they evil", it's "oh, a new person arrives at the castle and guess what, they want to kill Uther for legitimate reasons but must be stopped because he's a main character". It's only the season openers and finales that really advance the plot, up until the latest season (4) where it's fiiinnaaaallly got good and pretty much every episode has been an original and engaging story (but still has time for a scene where it's implied that Merlin regularly sees Arthur naked as part of his job description).