Dressing for a stock room interview?

I have an interview for a 'stock movement assistant' position at Debenhams.

I haven't been given any guidelines on how to dress and normally I'd to go with a suit.

However, because of the position and taking part in related 'tasks' during the two hour assessment I'm not too sure - it might involve manual work.

Another thing about suits is that I don't really like them. I have several, but the trousers on the two or three that are suitable (others are too formal, loud etc.) are too loose for comfort now (they seem baggy - my waist and thighs have shrunk but). My chest has gone up a size.

I have many blazers and many shirts. Should I go with that instead?

Does plain dark mint (colour) blazer, beige (large-) checked shirt and formal stone trousers sound suitable?

Should I wear a tie? I hate ties.

Any experience/recommendations? I've never had an interview before and this is my first proper/formal job - bit nervous.

Thanks.

(interview is next week)