I'm a third year chemistry student at Lancaster University. I would say that hours can vary from week to week but that the workload is high. There are lots of smaller deadlines and then exams at the end of the year so always something to be working on. However, this is better for me as it means that each piece of coursework is weighted less, which helps to take some of the pressure off.
Also, there are quite a few contact hours for practicals, workshops and lectures. I would say that I'm in uni at least 15-20 hours a week and then there's the courseworks and wider readings to do outside of that. Personally, I like being timetabled in uni a lot because it means that there is less self-directed learning time than there is in a law or history degree for example. A typical day can vary from a couple of lectures to a 9 hour lab.
Hope this helps!
-Beth (Lancaster Student Ambassador)