Hi,
I think that you could very well prove to be an attractive candidate to a university. Though marks are a definite consideration in admission decision, they are not the end all of the process. University administrators look at the entire 'candidate' - your work experiences, travels abroad, community service involvement, honors and awards, publications (if any), and leisure activities and sport all combine with marks to form a candidature profile. I would suggest finding a programme that interests you and writing to the convenor and explaing exactly why you connect with the program and what the criteria for selection are. Another useful website for answers concerning postgraduate life in the Uk is www.postgrad.com. Hope this helps!