I've got an interview for Law but in the same position as you where I have no idea what they'll ask. I expect it'll mostly be based around your personal statement, so I've gone through mine and highlighted anything they could possibly want to talk about. They'll probably ask why you want to do the course and if anything is in the news about Electrical engineering they may ask you about it. They shouldn't expect you to know in detail about the subject. When is your interview?