Interview at Shoosmiths firm

Presumably you are a law graduate? This is a paralegal?
If its in Northampton be sure to have a look around.
Some firms prohibit paralegals from applying.
Surely only they can tell you that or maybe you will get to chat to an actual case handler. They will be able to tell you what it involves. Look carefully at the sort of cases. Might be debt collection or ambulance chasing stuff.
What kind of questions should be your typical ones and just look at the job description. You must have some idea as you applied for it.