Were is this assessment for? I applied to John Lewis Liverpool on the 10th still have not heard anything back yet? how long do they take to get back to you? Don't think a blazer will be mandatory you just need to look smart!
I worked at john lewis over christmas, and at the assessment day everyone just wore black smart, you dont have to wear a blazer, i just wore a smart skirt with a chiffon white top with a black cardigan...the assessment thing is just to see what you know about john lewis (so i suggest you remember a few facts from wikipedia ) then you go in groups and sell an item they give you to that group (all while you are being observed) ..its actually quite fun :/ haha ..hope it goes well