Hi Matt,
I started my IT career in 1987, and I'm still going strong after 25 years, so I'll give you my view based upon my own experience.
Basically, I wouldn't plan too far ahead. Just get your feet through the door, get some useful experience on your CV, and that will be a good grounding for the rest of your life. At an early age you should get some high profile names on your CV; in other words the organisations you work for are as important as the work you do. And getting to know roughly how the business works is as important as technical skills. Developing your soft skills is just as important; showing that you can work in a team; showing that you can work alone; showing that you can follow specifications; showing that you can work with no or poor specifications; showing that you can discuss issues with people at as senior a level as possible e.g. management even directors; showing that you are not stuck rigid to one type of methodology; showing that you are flexible in your working arrangements. You need to get this type of stuff on your CV over the coming years.
At uni I assume you are taught the "correct way" of designing software. In a work environment, what you can and cannot do is normally restricted by budgets, historical working practices and regulations. This often results in having to take short-cuts, making guesses or developing alternative methods just for one particular workplace in order to fit the solution into their budgets, timescales, company policy etc.
And the three most important things in software development are 1) testing, 2) testing and 3) testing. It doesn't matter how great your design is, if it fails when it is implemented you get egg on your face. All software is implemented with faults so testing error handling is as important as testing for successful outcomes.
As for career paths; the longer you are in the game the more pigeon holed everyone will try to make you. Always take the opportunity to try and use different bits of software to prevent this. A few weeks of something is more than someone who has zero weeks of it and recruiters pick up on it. Being just an expert at software X isn't much good if software X suddenly goes out of fashion. As for PM, I've yet to meet a happy, smiling PM.
That's my pennies worth.