You may have made a mistake, but it isn't a fatal one. You need a path forward.
First, your undergraduate professors can still have credence in writing recommendations, but you need to keep in contact with them so you aren't forgotten. They can probably give you advice now on your current situation.
I assume that you are early in your European studies. ...
A) ... I won't be able to get good letters of rec
Are you required to write a dissertation or conduct a large project or similar? If so, then the supervisor of that work will be well positioned to write a letter of recommendation.
B) ... many students don't take their studies seriously
probably because there isn't the pressure of student ...