Ive done a year of Civil Engineering at uni so i might be of some help. The modules i did were 2 mechanics modules which were aimed more at general engineering applications, a maths module, geology, fluid mechanics, thermodynamics, a module looking at how materials behave under stress/strain and that kind of stuff, and a surveying module where we learned how to use bits of equipment and how to survey areas of land. there was also a drawing module where you start looking at plans and get an intoduction into using basic CAD.
In the end the course wasnt for me, i swapped to a different one, but there were loads of aspects of it that i really enjoyed. Even if your not sure about the civils side of things, most university courses put all engineering students together for the majority of first year, so if you find that you change your mind between environmental or civils, there shouldnt be much of a problem is swapping over, or even to something like mechanical or aerospace if that would interest you?