Journalism is not a stable or steady career at all. It’s been dying/transitioning, etc. for a long time–at least the last 15 years–and I think will continue to experience some serious growing pains as we continue to transition into digital/the world where no one wants to pay for news (let alone physical copies of it). Specifically, there will be fewer and fewer full time positions, thus making it a more unstable career over time. But, if you are a) passionate b) good at it c) exhilarated by instability (not always knowing where your next job will be, etc.) and d) from a generally comfortable financial background (ie: your parents will support you at times, especially starting out), then it can be a very fulfilling career.
I can tell you, anecdotally, that I possessed a and b graduating from a top ranked journalism program almost ten years ago, but my complete inability to handle c and no d meant that I did not become a journalist. I work in marketing instead because it provides steady, long term work opportunities and scalable pay but with similar persuasive writing opportunities. My peers who are journalists mostly freelance/do contract work and ALL of them (save maybe 1 or 2) had their parents pay their rent/living expenses for 2-3 years out of college while they interned for either free or low pay in high cost cities. Journalism, IMO, is not a stable industry, and if you crave stability, it will offer undue stress. I was just not built for it, honestly.
Investigative journalism is, indeed, a fascinating arm of journalism but not one that is easy to get into, and not ideal for an introvert. I am also an introvert who has social anxiety (I hate talking to strangers) and found reporting news PAINFUL (and thus focused on features/criticism), so you have to do some real soul searching because investigative journalists generally butt into other people’s businesses and really put themselves out there to get the story.
There are many forms of journalism. Broadcast can be television or radio, and it’s not all on air jobs. Most broadcast journalists end up being producers as opposed to on air talent, so it’s all about learning to package stories in those mediums. “Print” journalism can mean newspapers, magazines or online/digital publications. Newspapers and magazines are dying, and it is not easy to get the scant positions available at the print pubs that are left, at least not right out the gate. You can work your way up to those positions. Digital is booming, though a lot of the work is contract/freelance. There are all sorts of arenas/subjects/specialties you can pursue within journalism–news reporting, sports, entertainment, criticism, lifestyle, science, politics, features… I would say pick the thing you’re best at writing–we all tend to have a niche–and pursue that thing. News, politics and features tend to be the most obvious avenues into investigative journalism, though not always (I’ve seen some impressive investigative features published at Buzzfeed on the entertainment industry).
You don’t have to study journalism to be a journalist, though in some cases it helps–most places don’t want to train you on the job and there are some basics of journalism you can, therefore, pick up in school. But some of your word choices/descriptions sound like you’re in the UK, and it’s a different ballgame there anyway. Don’t major in journalism–pick something to read like English or History. That said, the world needs more competent science journalists, so don’t discount that! (most journalists are crap at writing competently about science!) If you’re, indeed, in the UK you are also at an advantage b/c the print industry isn’t dying as rapidly as it is in the US. Look for work experience at your flagship newspapers and see if you like it. You don’t have to be studying journalism to do one of those work experience rotations. When I did one through my US university, we had several UK kids doing short term work experience at the same time and they definitely weren’t studying journalism. Some were gap year students.
Honestly pay is bleak. Until you reach the upper echelons of the industry–which is rare–you’re making sub-standard wages. The starting salary for a journalist in NYC hovers between 30 and 35K a year… which is what it was when I graduated in 2006. And that’s if you can land a FT job–they’re rare. Honestly I think its criminal how little journalists are paid. Over time, if you establish yourself, and especially if you’re a good freelancer (hustling for $$$) you can earn a tidy sum, but you’ll likely need to a) live with roommates or b) have your parents help support you and/or c) marry someone who brings in a much better salary to balance things out.
So the good with the bad. Study something that interests you–not journalism–but try out some journalism work experience and see what you think. It’s a really awesome profession, but comes with caveats. If it were more stable (or my family was rich), honestly I’d be doing it.