Neil45, you're not attending Malaspina University-College by any chance, are you?
I think we've all had discouraging marks somewhere along the line, but the key is perseverance.
I've had a few marks I wasn't very pleased with but I never got upset with myself.
I made it my goal to find out why it is I got the mark in the first place and what I could do to improve upon it.
Of the things I learnt last year in my first year of undergrad the lesson I took home with me the most was to avoid stress by any means and try to laugh a little.
Good luck and don't ever doubt yourself.