Its very informal with questions about what you are doing or have done education wise, how far away do you live, do you have a car, what is your flexibility.
There are no 'where do you see yourself in 5 years time' or about why you want to work for Morrisons.
You should wear something reasonably smart, they will be give a shirt, apron, jacket if needs be but you need your own black shoes and trousers. You can wear long skirts if you are a woman, they might be ok on the checkouts but i would suggest trousers instead.
Try to keep makeup to and jewelry to a reasonable level, so not 10 rings and 10 bracelets. Some managers will ask you take makeup or jewelry off if you have too much on in their opinion.
When at the interview, look if you can see the uniform guide, it tells you what you are expected to wear in much more detail. ( in my store its next to a big mirror)