If this is in the wrong forum feel free to move it.

So basically i am 16, just finished comp and got a job interview at a store called boundary mill (http://www.boundarymill.co.uk) Its a place that old biddies shop at basically, now I no the standard rule is to wear a suit to a job interview, however because it is a part time sales assistant job I was thinking of simply wearing some black trouser ( there jeans but you can not tell ) and a simple plain v necked t - shirt (grey) and a simple jacket, will this be appropriate ??? Any advice is thanked in advance.