Emilia - it's ok (for some reason I like it much more than Amelia which I'm really not keen on). Emmie is cute. Don't like Millie.
Rosanna - like it. Rosie is a very sweet nickname for a little girl
Natalia - lovely. Very elegant and quite unusual. Tally/Talia both nice too.
Tamsin - not keen but do think Tassy is cute as someone upthread said
Felicity - love this. It's my favourite on your list.
Serena - it's ok.
Polly - cute. Quite like it.
I'd go for Natalia if your husband can't be persuaded on Felicity.
Other ideas:
Arabella, Aurelia, Annabelle, Abigail, Aurora, Alicia, Alexandra, Ariana, Adriana, Adrielle, Arianne, Beatrice, Carolina, Christina, Catalina, Cassandra, Clarissa, Cordelia, Calista, Christabel, Coralie, Camilla, Claudia, Cecilia, Cynthia, Dorothea, Delilah, Eloise, Eleanor, Evangeline, Elisaveta, Francesca, Florence, Felicia, Fabia, Fenella, Fernanda, Georgina, Giovanna, Genevieve, Hermione, Harriet, Henrietta, Harmony, Helena, Isabella, Imogen, Jessica, Joanna, Juliette, Julianna, Josephine, Jocelyn, Katerina, Katherine, Lilliana, Lucinda, Lydia, Louisa, Leandra, Lavinia, Larissa, Leona, Miranda, Matilda, Melissa, Madeleine, Marianna, Natalie, Natasha, Nadia, Nicolette, Ophelia, Octavia, Olivia, Philippa, Peronelle, Penelope, Pandora, Paloma, Rebecca, Rhiannon, Rhianna, Rosemary, Rosalie, Rosalind, Seraphina, Sapphire, Sabrina, Saskia, Susannah, Sophia, Stephanie, Samantha, Tallulah, Tabitha, Teresina, Victoria, Vanessa, Violet, Viola, Valentina, Veronica, Xanthe, Xenia, Yasmin, Zara.