I think I found out who played Sally Anne Perks in the Harry Potter and the Order of the Phoenix Movie. I found Sara Bispham credited as Sally Anne Perks in the full cast and crew on IMDb.
IMDb Links[]
Full Cast- https://www.imdb.com/title/tt0373889/fullcredits?ref_=tt_cl_sm#cast
Sara Bispham’s Credits- https://www.imdb.com/name/nm1876138/?ref_=ttfc_fc_cl_t83
Check them out and tell me what you think.