I remember I wanted to work vaguely in "media". I had no idea of the different jobs in media and everywhere I tried to research I hit dead ends. Eventually managed to speak to a friend's dad who was incredulous that I had no idea of the different jobs (which made me feel frustrated because I was trying!) and then said, god, whatever you do, don't study "media" at university.
Seems obvious now but when you're 14 and all you've ever known is school and possibly your parents' industries (if they even have one, my mum was a waitress and then unemployed due to long term sickness) and the school are nicely pigeonholing everyone, oh you want to do media, go on this media course... you just have no idea.
I don't want schools to go back to "You're useless and will never amount to anything, now do a typing course, girls can't be doctors!" but I don't think that giving wildly inaccurate career advice is helpful either. What young people need is low status jobs which can lead somewhere and which, crucially, give you an insight into a particular industry and how it works so that you can work out where you fit in that one, if you indeed fit into that one at all. Once you leave school and start meeting other adults you learn loads about different jobs, but teachers and career advisors just don't seem to know in enough detail.
College was great for me - all tutors were ex-industry workers. IMO that would be a great asset, if secondary school science teachers had worked in labs or engineering or as a vet, english teachers in publishing or journalism, etc etc. It's not realistic but it would be fantastic for young people.