LOL - no pressure needed and I already did.
Western Europe's early season mayfly is the Large Dark Olive (Baetis Rhodani). Here is my fav patten for it (second only to using a CDC&Elk LOL). Just change size and color to match the bug you wish to imitate:
Z-Dun (Large Dark Olive)
Video here - best viewed in HD, and a larger window:
http://www.youtube.com/watch?v=P8sKtwjY4k4
Cheers,
Hans W