So at A-level the top grade (A*) requires 90% (sort of, but bare with me...). For a degree the top grade requires 70%. You don't need to complete every problem sheet, or be perfect in every bit of labwork.
Aim for a good 2:1 in year 1, and then build on that for year 2 onwards when you've got to grips with time management and your lecturer's expectations.
And do some other stuff... not just everything Engineering.
in other words, try to enjoy it. not force it.