Just going to write this here to help anyone for the future. My interior design interview consisted of 16 other applicants all together and the lecturers split us into two groups.
In our groups we sat around a table with our portfolios and were one at a time asked to talk about our favourite piece of work and our least favourite. We then went on to show our whole portfolios.
They might not do it the same each time, but this was how it was for my group.
I probably worried about mine way too much, it was honestly really relaxed. I didn't even worry when I came to talking about my portfolio because I knew everyone else was too busy concentrating on what they were going to say for theirs.