most people have spoken to the uni/course have a system where nothing in first year counts then in year 2 you do X credits and year 3 do you X credits, all of those percentages are averaged with a weighting towards final year, so anything you do in final year 'counts' more... I got a 50% on an essay in my second year and worked out that compared to getting 85% (a strong first) I'd lost 0.5% of my degree, obviously that is a teeny tiny amount! you will absolutely be able to work off a low mark