In my TA interview I was asked specific details of all the experience I had working with children previously...if you have your own children obviously mention this too.
Ask if the TA roles at the school are split into SEN/EAL roles or if they are mixed, do you know if the job is to support one particular student or whether you'll have a very mixed timetable for all yeargroups. (Unlikely but if they were to give you a choice I would opt for a mixture-variety is the spice of life and working one on one with the same student 25 hours a week can be tough).
Ask about the school's behaviour policy and if TAs are supported fully delivering sanctions as teaching staff would.
Find out if you would be required to do any break duties, bus duty, after school club hours in your interview so you don;t have any future surprises. At my school TAs are not expected to do these but I know loads of schools where they are.
Is it a secondary role? I work in secondary myself.
If you have a preference or skill in a certain subject area then definitely mention this. Personally, I thrive in humanities/arts (but am hopeless at maths).
Be friendly, warm and never forget that the priority is the students and it's them you're there to help. With this attitude they'd be silly not to snap you up.
Hope you see this tonight
Good luck!