What courses are you missing for the requirements for 3fe3?
If you're just missing one course (2i03) there's still a chance that they may waive the prereq.
They are offered at different times in August so you can take them both after your third year.
So for next year make sure you take 2e03, 2i03, 2q03 and 3l03 (better to take 3l before 4fe3, it'll make things a lot easier from what I've been told)
Prerequisite(s): One of EARTH SC 2E03, ENVIR SC 2E03, GEO 2E03, ISCI 2A18; and one of EARTH SC 2I03, ENVIR SC 2I03; and registration in Level III or above of Honours Earth and Environmental Sciences; and permission of the instructor.
Prerequisite: Registration in Level III or above of an Honours B.Sc. program in the School of Geography and Earth Sciences. Credit or registration in EARTH SC 3L03 or ENVIR SC 3L03 is strongly recommended. Prerequisite (Beginning 2012-2013): Credit or registration in EARTH SC 3L03 or ENVIR SC 3L03