Yes! The only place to go is the Nightingale Patisserie on Nightingale Lane. The owner is Dario who makes the most amazing cakes of all shapes, sizes and decorations. I’ve been using him for years, both for kids and adult cakes.
I would recommend Clare from Willow Bough Traditional Tea Room in Wimbledon, she is experienced and can cater for big groups. Her number is 020 8540 8080 and email firstname.lastname@example.org she will be able to advise on costs too.
I have gone to Laura Amos @ Deli Desserts. She used to have a stall on Northcote Road (have a look on instagram @thedessertdeli - and you will see some of the amazing cakes she does. She is pretty amazing. Her email address is email@example.com or phone number 02072280511 (her kitchen number).