She needs to research businessesin the area, so industrial sites, think small to medium businesses. Get the names of the businesses, google them, and then write personalised letter or email to the HR / PA / MD, either drop off letter or use LinkedIn to network.
I'm a senior manager, very busy at work, and would love a 16 year old with a bit of get up and go in them, after some hands on office experience for a few weeks. They earn a bit of pocket money and I get some admin type projects competed. I'd never advertise because 1) time in responding 2) it is a general bit of work to be done, not clear job description, 3) I can't be ageist, so as much as I'd love a young person to work for me, I can't state it (despite the work being most suited to a young person)
So, she needs to send speculative cvs and covering letters to normal businesss, don't just focus on catering.
And if she's in Staffs, pm me!