I've been vegan for 1 and a half years now, and for 1 of those years I had shared a flat with others (I'm staying in a studio this year though).
My advice would be:
1. Take the top shelf of the fridge - that way you don't risk having anything leave or drip onto your food.
2. Wrap your open things in cling film, and put any leftovers in tubs.
3. Don't worry about anyone stealing your milk! People turn up their noses at plant alternatives, even if they've ran out of their own milk (I've offered multiple times).