We bought 3 or 4 little cartons of ready made formula, as LO was due on Christmas eve and I was terrified it would all go tits up (excuse the pun) over the bank holidays. DD rocked up 5 weeks early and is now 11 weeks old - cartons remain unopened in the wardrobe but it was reassuring to know they were/are there so a mad dash out isn't needed with screechy wailing baby, if the need ever arose.
We bought an Avent starter pack with a few bottles/teats and microwave steriliser, again iin case things went wrong (I was clearly quite anxious with hindsight). Cheap and has come in v useful as I express now. I would hold off getting a pump until LO is here.
Breast pads, muslins, cheap stretchy vest top under a looser top works for me when I'm out, a couple of good nursing bras (I got fitted after the birth as she was early).
I got some lansinoh cream, my mw said if your latch is good you won't need that. And she was right 