Pauline Quirke would have been 17 when Swap Shop started so it's just possible. However, I've looked in the BBC INFAX programme database and the only appearances by Dame Edna on Swap Shop (that are listed) are both in 1982, by which time Pauline would have been rather too old to be in the audience. This is not entirely conclusive proof that it wasn't her, because it's possible there were other appearances by Dame Edna that weren't listed in the database, but them's my findings and you can make of them what you will.