Hey, I don't really have any advice, but I'm in the exact same boat (semi-finalist for study at East Anglia) and I haven't received anything about an interview either! Maybe a lot of the notifications are later this year? (holding onto the hope that it isn't just a flat rejection)
I know there have also been discussions upthread about how not every program does interviews, and even programs that do do interviews don't always interview the person who will ultimately be the winner. So, who knows!