Ms Davey was provided with a full induction, including learning how to make pizzas, how to serve customers and the health and safety regulations.
Idea Services support worker Donna Brown said for Ms Davey, finding a job that paid was huge.
"Within this programme there's no guarantee for paid work ... but Soph did so well. She can now buy her own magazines or a coffee, for her that is huge."
A major change in Ms Davey had been her ability to make eye contact, she said.
"That's the biggest thing. Soph used to always look down at the ground but her confidence has grown so much she now looks at you when you speak to her."
Mr Nixon said Ms Davey breaks into a sprint as soon as she hears a customer coming through the doors.
"She really enjoys working with other people. It's also been really good for our own staff and their morale; they have taken things on board and we always have a laugh when Sophie's on."
Ms Davey said she loved working on the till and providing good customer service.
Mr Nixon said the biggest challenge for her had been people's perceptions of what she couldn't do.
"We've had 54 people through the scheme since it started from head office in 2013 and, I know without a doubt this is a good initiative. We are definitely keen to do it again. Sophie is always asking questions and is so keen to learn ... although we didn't have to offer her a job, we did because she was so great."
Mrs Brown said schemes such as this provided opportunities for disabled youth to gain employment. "On the job training means they can turn up to another job and actually show they have the skills and experience to work. It makes a big difference ... it means employers won't find them as difficult to hire."