I used leftover grids from making their NIC condo to make their recovery cage
I don't remember where you live (assuming you've mentioned it) - I've met so many new folks since I got back to the forums a week or two ago, lol. I do prefer the kind with both probiotics and prebiotics... in the US, BeneBac Plus has both. In the UK, all major brands seem to have both.
Metacam comes from the vet - most vets send it home with you after spays automatically, but for some reason not all of them do... just make sure they give you some before you take them home. They shouldn't need it until the second day because they should get a pain relief shot at the time of their surgeries that lasts for 24h (but double-check to make sure).
~ It's good to have critical care food if you can find it (available though some vets, at some pet stores and can be bought online, though it can be hard to find... leithpetwerks sells it online, that's where I got mine...) - definitely go with apple-banana; I had a godawful time trying to feed the anise flavor to my bunnies and other people said their bunns hated it too.
~ You'll want a syringe (6-10cc is a good size) with no needle in case you have to force-fed.
~ Pedialyte is good to have in case they don't want to drink much.
~ If you use water bottles normally, it can be good to offer a bowl for the first day or two - easier for them to drink.
~ Vetwrap (no-chew bandages) and a couple gauze pads are good to have in case they won't leave their incisions alone (available online, at many feed stores and through most vets) - it's a great way to avoid needing to use an e-collar on a bunny.
~ Have some of their favorite fruit/treats on hand - my vet said to let them eat whatever they wanted for the first day or so, like a sick kid getting lots of ice cream.