I think that it depends also which university you go to. I studied at a very well-respected one, which rejects many more potential students than it accepts, but I found that during course weeks I didn't have to be in University more than 4 hours per week, because all the lectures were added on to the intranet. So I only had to be in University for the tutorials. Of course it was helpful to actually attend the lectures sometimes.
It all boils down to teaching style. In my University that I did my first Degree (I did Nursing as a shortened post-grad course), lectures were more like tutorials, we got taught but could interrupt and ask questions, take the teaching off to an interesting tangetial subject, expand, and so on. If you didn't attend the lectures, you really were missing out.
In my Nursing lectures, you sat, and listened, and did not speak. All that the lecturer was talking about was well backed with a power-point presentation, so you really didn't need to be there physically.
Studying, again, was down to personal preference. Some students were plod and prepare, so studying at University each day, in the library or a study room. Others were cram and cluster, so did little during the term, but were there every hour the Uni was open in the few weeks leading up to an essay/exam. Yet more were consistent studiers, but due to family life organised themselves with all the material they needed so that they could study at home in the evenings.
If you want to do it, you will fit it in somehow. It is very doable.
WRT placements, do your best to be keen, motivated and interested, rather than 'clock watching' (even if you are on the inside!) and then it is amazing how flexible they will be. Students who moan about outside committments and how they need to be away by this time, or can't do this and that, tend to be given the worst shifts, because there is a perception that they are a bit slack, or have an attitude problem. Certainly my experience is that students with childcare committments who came on shift keen and eager, then mentioned the childcare hours and asked if there was a way to accomodate them, got to pretty much dictate their hours, because they ameliorated the concerns about their committment by showing a good working attitude early on.