They take you down to the operating theatre & get you all ready. A midwife came and 'dry shaved' me beforehand - lord only knows what it looked like down there as my bump meant I'd not seen it for months! There'll be form-signing and a consent discussion too.
In the theatre room after they put the spinal in (this hurts but only when the needle goes in) they immediately lie you down flat on the table - after sleeping almost upright, propped up with a million pillows for 4 months previously, this felt very strange and I felt like I couldn't breathe. They will reassure you.
They will then test how numb you are by poking & prodding various parts of you and asking you if you can feel anything. They then asked me to try and lift my legs - it's a VERY strange feeling when you can't!
Then they put a really high screen up, you really won't be able to see anything after that, just the tops of the staff heads.
Depending on why you're having a planned CS section, they'll be numerous staff coming in and out. I was in for polyhydramnious, so I remember seeing one poor member of the team absolutely soaked in amniotic fluid - they came round the screen and showed me!
I know people have described a CS as feeling like 'they're (the doctors) doing the washing up' inside of you but I honestly didn't feel a thing!
Wish I'd thought about taking my own painkillers in for afterwards. For the time hours afterwards, when the spinal wears off and you've been moved to the post natal ward and there's no staff about - you will need them.
Other than that, like PP have said: big nighties, big knickers, lots of huge fanny pads.