Lovely name; would use it happily.
Most Margarets I know go by Maggie if not by Margaret itself (my cousin, for instance). I quite enjoy Maggie. And I once knew a girl with the full given name of Peggy, which I found refreshing. When I was younger I liked the idea of Margot and Megan, but I've got over that. And I've never fancied Greta, Gretel, Gretchen etc.