undoubtedly, having a deep sound knowledge of maths is important to any engineering degree.
But what about people who did maths in high school, did something else, then wanna do engineering later in life?
What about people who only did general maths and want to do higher maths?
Not all is lost if you only have a basic knowledge of maths. you can still be an engineer.
At the university of Sydney (and I'm sure they have something similar at other institutions) we have things called
1. Bridging courses
2. Maths learning centre.
to explain.
1. bridging course = a short course in teh holiday to teach you everything you need to know for the required prerequisite (so they don't teach you stuff you don't need. ie permutations)
2. Maths learning centre = a library/room where there are extra tutorials, online help learning material, extra tutors always avaliable to people who haven't done maths in a while or who require extra help.
No doubt, not having done 3U will mean you will be disadvantaged.
However, I honestly believing the best mathematian WILL NOT be the best engineer. For engineering is much more about logical thinking, creative problem solving spatial and critical thinking that the ability to prove alpha beta sigma blahblah equals someother random greek ensemble.
All the eiganvalue, statistics, double integral stuff i learnt in first and second year, i HAVE NOT TOUCHED later in my engineering degree.
My advice - if you're prepared to put the effort in - go for it!
Help if out there - look for it