There are people aged from 18 to 40+ on the FPP. Some are just out of school with little in the way of work experience, while others had careers as doctors, engineers, IT managers etc before joining. And not everyone on the FPP is British. So it's clear that a wide variety of people have made it, and those who don't make it should not look to their age, past career, or nationality as the reason (as long as they meet the entry criteria outlined on the BA FPP website).
Good luck to those still in the running!