I wore trackies and a singlet early on, got in the shower and got nude and stayed like that! Although I did have knickers on as I was leaking fluid still quite a bit! I had a gorgeous pashmina shawl as well that I got DH to drape over my shoulders when tehre were too many people in the room and I wanted some coverage.... I was induced though and it is hard to get anything off and on your arm with a drip in As someone else said, whatever you feel comfy in, lots pf people use a big t-shirt too and I loved the nana nighties once she was born as I had a c/s!
Good luck!