For unusual, I like Cordelia, Amelia, Elvira, Genevieve, Abigail (Abby), Constance, Henrietta (Ettie), Josephine, Dorothy, Florence, Jessamine, Hortence, Gertrude (Gertie), Matilda (Mattie), Virginia (Ginny).
More usual but also with an old feel... Beatrice, Rebecca (Becky), Elizabeth (Bess, Bessie, Beth, Betsy, Eliza, Liza, Lizzy), Esther, Grace, Hope, Jane, Isabella, Juliet, Katherine, Judith, Lorraine, Louise, Margaret, Maxine, Molly, Nancy, Natalie, Phoebe, Ruth, Savannah, Vivian, Victoria.
Hope it helped! :P
Funnily enough I created an Elizabeth as a character when I was younger who went by a different nickname every school year. Zab was one I came up with.
Long, older names with unexpected nicknames, hmm... trying not to repeat names already suggested.
Cassandra - Candy
Caroline - Oli/Roly
Rosemary - Rory/Romy
Eleanor - Lenny
Dorothy - Ro, Dora
Florence - Ren
Victoria - Tor/Tori/Ria
I don't think you could use Carlotta as a name for an 1800s English girl unless there's some Italian heritage in there. Names from other nationalities weren't very common at that time. If you like Lottie, Charlotte would work.