Put it this way, I got a 'U' in Maths. I put it on my UCAS application (and ok I'll be studying web design so IT is the biggest prority I guess), and received an unconditional offer. I still think it's my A levels at grade AAA which pushed it through though.
When I 'failed' at school, I went to college and turned it around. And what I achieved at the end of my A Levels was so pleasing compared to school.
Never lie on the application though, it may come back to bite you...