For the interview it doesnt matter if its skirt/pants...just as long as its professional.
They are reeeaaallly trying hard to enforce the business casual everyday attire for vet students, but it is simply not reasonable. From 8-12 you have lecture, from 1-5 you get "nothing in modern chemistry will ever get that SMELL out" disgusting. Even after showering twice, plus fresh clothes, you still smell.
So you get the 1st year class giving it a college try for the first 2 weeks and then it goes out the window (as it should be imo!). As it draws near finals time everyone ends up wearing whatever was left on the bedroom floor last night.
They are however strict about no open toed shoes in every lab...so you could wear sandals in morning lecture, but you'll likely get out of the flip flop practice.
Its usually jeans & t shirt, then bring scrubs + lab coat + rubber boots in a plastic bag. Spare yourself the agony of laundry and get 3-4 pairs of scrubs, then wash them all 1xweek separate from normal laundry.