Interview tomorrow, help!?

Hi guys,

I've got an interview tomorrow with Tesco for a checkout/grocery/meat job. I've applied for all 3 jobs and they've called me in, but they haven't specified what job they actually think would suit me best, so I'm guessing this could be covered in the interview. I have a few questions...

1. What sort of questions are they going to ask me? If you've had an interview with Tesco before and you can shed some light on this subject, I'd be very grateful! If you know what sort of questions they will ask me, how do I answer them?

2. How long (on average) does the interview go on for?

3. I've heard they sometimes do group interviews for candidates now, but I'm not sure if I'll be taking part in one or not. How will a single and a group interview be different?

4. Last question, I've always struggled to answer the question 'what do you think you can bring to our company?' I just don't know how to answer it!

If you guys could help me out, I'd be so grateful! I'm pretty nervous already and helping me out would really help me calm down and do well in this interview :-)

Thank you in advance!