Katie is blissfully happy as she prepares to tie the knot with Home Farm boss Declan Macey (Jason Merrells), but the big day won't be without drama as Declan's half-sister Megan discovers that he has been plotting to make sure she doesn't get a penny of the festival profits.
Here, Sammy Winward - who plays Katie - chats about her involvement in Emmerdale's birthday and the live episode.
Are you enjoying Katie's current storyline?
"I'm absolutely loving it. We've got such a good group at Home Farm. We can talk to each other but stay professional and we all have a good laugh.
"I've always enjoyed it at Emmerdale - I think that's why I have been here for so long. I've been given some amazing opportunities."
Is Katie definitely in love with Declan?
"Yes, I think she really has fallen for Declan. At this moment in time, she's not really interested in the money. She probably does enjoy that side of it, but Katie falls in love quite easily."
How will next week's ceremony compare to Katie's last wedding?
"Last time she got married, it was a very simple wedding and quite a simple dress - but this time Katie looks like royalty. She is practically wearing a crown!
"The dress is beautiful and very expensive. I think this might be the start of her realising that she does quite enjoy Declan's money."
How involved were you when it came to Katie's wedding dress?
"I had five fittings and it's been brilliant. I feel really lucky as it's an amazing experience to have a dress fitted to you so perfectly. It's a beautiful dress, very simple and classy.
"It's the complete opposite to Chas. It really shows the difference between the two characters. Lucy definitely drew the short straw with that one!"
> 'Emmerdale' 40th anniversary - full coverage
The wedding may not run smoothly as Megan storms in after discovering that Declan is planning to rip her off…
"Well, there are a few things that could stop the day from running to plan, but it's an Emmerdale wedding so nothing ever goes to plan. Hopefully they will get married!"
What can we expect from the 40th anniversary week in general?
"Expect a lot of storylines to climax, but also the start of new ones. It is going to be a massive day for a lot of characters in the village."
How does it feel to be playing such a big part in the milestone episodes?
"It's amazing. The atmosphere is brilliant at the moment. Everyone knows we have such a huge event coming up, but we're all in it together. It's very nerve-racking but really, really exciting."
Have you ever done live television in the past?
"No, never! I think it will feel like doing theatre, but much more scary because if you mess up millions of people are going to be watching."
What are you most worried about?
"I'm most nervous about giggling. I do it at times when I shouldn't. If I have 30 people waiting for me to do a scene and I get the giggles, it makes it a million times worse.
"It may go the other way, because the live might completely freak me out so there is no laughter inside me. Nicola, Jason and I all set each other off!"
Emmerdale's anniversary celebrations air all next week on ITV1. Emmerdale Live airs on Wednesday, October 17 at 7pm. Get the Inside Soap magazine on your iPhone or iPad