It depends on the degree/department/university. How you perform in first year can be used in weightings used to govern which degree type you can graduate with. For example, if you slump in 1st year of a MEng degree, you can be downgraded to a BEng or even a BSc if your 1st/2nd year GPA is below a certain threshold.
Please stick in and try your hardest and also don't forget to enjoy yourself too whenever you can. Both come hand-in-hand with one another.