If you think about it, soaps will quite often be transmiTting on a different day to the fictional action. If they didn't, we would never see anything at the weekend and whilst it is rare, it does happen sometimes that it is mentioned it is a Saturday or Sunday - usually when it is a date like haloween, Bonfire Night or a characters birthday.
Also, you often have multiple episodes taking place on the same day due to the intensity of the action like The recent helicopter crash where the episodes transmitted on Tuesday, Wednesday and Thursday all ran on from each other on the same day. So which of the 3 days in the 'real' world was Debbie and Pete's wedding on?
Same with shows like Casualty and Holby city which sometimes run straight on or they state that the previous episode was the previous day when in fact a week has passed in the real world.
So, it's a moot point. There are days we don't see, but they don't always have to be the same ones. What i mean is, we don't always see Monday, Tuesday, Thursday and Friday on EE whilst missing Sat, Sunday and Wednesday every week.
Re the costumes - yes it is unbelievable on such short notice but they are actually meant to be pretty close to Leeds which has a huge shopping centre so they would be able to pick up decent costumes there.