Good luck. I know you're already done it now, but the key to the group interviews is just be yourself.
Don't be overbearing, and don't be timidly quiet and shy. When you get split up to smaller groups to do your task, if your group isn't doing much, then take the lead, throw some ideas forward and ask the others. Don't be too bossy, but it shows initiative and willingness to do something/have a go, while including everyone.
Just be normal, polite, helpful and chatty but not overly so and you'll be fine.
If you get a one to one interview, it would be good to read up on the Asda values. These are
- Respect for the individual
- Strive for excellence
- Service to our customers
Think about how you have shown these qualities in the past and maybe how you can apply themin the future.
It largely depends on who you get your interview with, it's likely to be the department manager on which you'll be working.
When you have your group selection, they have a few managers in there and they all note down the people they have their eye on.
Oh, and everyone is a colleague. Never staff, worker, or whatever...always colleague
If you need any more info, just ask
Edit : Just re-read your post and see you've already been called back for a 1:1?