Here is a simple way to play the melody to Scarborough Fair. You can find the chords to this song in my method book "I've Always Wanted to Play Guitar" If you have my method book, be sure to download all the music.
Here's a great "Campfire" strum for Pink Floyd's Wish You Were Here.
D D U U D D U U
D = Down
U = Up
Here is a video of the melody. You can play this for the intro to the song and you can play it as the interlude between the verses. I'll add another video soon with the chord strums between the melody notes.
And here's a video adding one simple strum on beat two of each measure.