Hi OP
I'm SL at an RG university and we have similar issues.
We start "coaching" our students right from the very very beginning- I'm talking open days here! Whoever runs the open days (especially post offer open days where we have more chance to actually talk to the students rather than just "selling" the programme) talks at some length about the difference between school and university making it very clear that at our university they will be expected to work very hard outside of class independently. We talk at some length about what that means and, actually, how exciting that can be!
Then when students first arrive, we hit them with it again in the first lecture of every module. We've used the gym analogy before to explain that they get out of their degree what they put in.
At the big welcome talk, we have 2nd/3rd year students there to talk to the newbies and we also get them to say a little something about independent learning as well. It sounds terrible but we always try and make sure these 2nd/3rd years aren't "typical" students from our university (from the SE, privately educated, posh, head-to-toe in Jack Wills) so that arriving students don't think "well it's okay for you".
We also have a teaching and learning contract which all students sign in their first seminars/workshops (we're humanities) which basically asks them to promise to put in effort, do the readings, read the Handbook etc.
After week one, when we're confident that students have settled we get very tough with students who aren't performing well. For example, at the start of each seminar I ask students for a show of hands if they've done the reading. Those that haven't I ask to leave the seminar. I've had a lot of grumblings about this in the past but the L/T contract we get them to sign protects us from their moaning and actually does eventually create a culture where students are working hard.
I make clear that they don't need to have understood the readings but they have to have at least done them. Our classrooms are then really nice conversational places where we can explore the readings together on the assumption that everyone's at least tried to understand them.
If there's a legitimate reason for a student not doing the readings, I ask that students email me in advance and I can give them something a bit more accessible to read if that's appropriate or I'll structure the seminar in such a way to not disadvantage them or I'll give them something else to do to then specifically report on (this might be reading a blog or watching a programme but they have to give an individual report on that so it's not really a cop-out).
It works well to do all of this stuff at the very beginning of the year so you create a good, hard-working culture from the get-go. There needs, however, to be some consistency across staff/modules; you need to be prepared for students grumbling at you; and you need to be prepared for students emailing with completely bullshit reasons for not reading or for them to come to you for help with planning their time.