Congrats! I was also quite nervous and I really wish I'd calmed my nerves sooner as it wasn't half as intimidating as I'd expected. The facilitator did her best to move us away from a competitive mindset, and that definitely helped. I was quite surprised about how personal the questions were. Think along the lines of: Why social work vs. other professions (for you), how your personal identity affects your work (referring to any volunteer or professional client-based work seemed fine), areas of today's world that would benefit from social work intervention. I really got the feeling that the interviewer wanted to get to know us as individuals, which I really appreciated, so focus on being authentic.
Last bit of advice would be: don't "arrive" too early and awkwardly stare at your fellow interviewees while your nerves ramp up. Be on time and get going!
Hope this helps a bit. I'm still awaiting a decision myself so hopefully this advice is sound!