Hi Hens and welcome to the Forum. Whereabouts is the PE12 area? You will need somebody who lives as near as possible. Had you considered contacting the local school or youth Club leader to see if they can put you in touch with a responsible older teenager? Or put notices in local shops? Our town has its own website and Facebook page, and if I didn't already have an excellent teenager (with parental backing if needed) I would try posting on these sites as well.
My 15-year-old teenager visits the flock before we go away, and I update her verbally on what I expect her to do, and then give her a copy of what I've said in writing. This includes daily jobs and checks to carry out, my contact details, phone number and email, and contact details for my vet. I pay her £15 for a week for a minimum of one daily visit (though her mum says she spends much more time than that in with the hens!) and the promise of an extra £5 bonus if I'm pleased with what I find when I get back, which she has always earned. She enjoys the responsibility, and on one occasion two years ago, when one hen had a bad prolapse, her mum stepped up and helped her isolate the bird and later to take it to my vet.