One route is through Hartpury
www.hartpury.ac.uk/university/facilities/equine/?gclid=CjwKCAjwhMmEBhBwEiwAXwFoEWwf1oReNe5y2_cKjex2D2ZOvbRLb9VXptdSzzGiz4hRhNmN6jmn-RoC3v0QAvD_BwE
but tbh I know more people who have had success working their way up and taking BHS qualifications along the way, or combining it with a career. That could be unfair though as I don't personally know any Hartpury graduates.
I'd say at 14 years I would be encouraging her to stick with her academic studies as well so she has more choice at 18. Your DD sounds like she has the right attitude but working with horses is as much as a vocation as a career tbh. They need care 24/7, Christmas day, in all weathers, and the pay isn't great. It's hard going. Early starts. Long hours. You have many ups and downs and have to be very resilient to succeed. And of course you can be seriously injured yourself. Sorry to sound so negative but the risks are there.
The benefits are huge too of course if you are an active, energetic person who enjoys working in the outdoors. And of course it's a great privilege to work with animals; hugely rewarding. One day is never the same as the next. And you learn so much each day. And the lifestyle is a very healthy one if you can avoid accidents.
How about having a look at this as a start ?pathways.bhs.org.uk/career-pathways/
And talk to as many people in the various branches of the industry as you can: breeders of all types, showjumpers, dressage riders, eventers, endurance riders, jumps and flat trainers in racing, vaulters, horseback archery, show yards, hunter yards, point to pointers, general liveries, pentathletes, working heavy horses, chiropractors, farriers, equine vets, saddlers, feed merchants, equine equipment and clothing retail, land management ...the list goes on ... .
She needs to talk to people in the industry and get as broad experience as possible in the holidays. Where you get work experience is important. If it's a good place with a good reputation, in whatever area of the sport, the contacts you make will be very useful later on.