Hi and welcome!
Vets that do work for shelters get to spay lots of rabbits, so that means they acquire lots of experience. That is obviously very good.
The main things to keep in mind in prep for a spay are f ex:
Get a hot water bottle or hand warmers, she might need warming up when she comes home.
Stock up in favorite food. Fragrant herbs like mint or cilantro are often popular. The most important thing is to get her to start eating post op.
Feed bunny before surgery. Send some food with her, hay and a favorite leafy green or piece of fruit.
Serve her water in a bowl when she comes home, she’s likely not in the mood for bothering with a bottle (in case that’s what she normally has).
Ask about painkillers. She’ll probably get a long-lasting injection at the clinic, but ask for a prescription as well so you can give her painmeds for 3-5 days post op.
Please ask more about whatever you come to think of 