My site www.theflutecoach.com has some free lesson series available, but I think they may be too easy for you if you are an intermediate player.
This '7 tunes in 7 days' series coaches you through some simple songs like nursery rhymes etc. And introduces essential concepts such as counting, articulation, time signatures etc. I provide links to all the sheet music as well. Feel free to have a look either way...
Eventually I will be adding intermediate level content, but alas it won't be for a little while yet!