Hi there! when I applied to the Uni here in the U.K, they took care of the matter. I know that they have a convention with an institution called NARIC, which evaluate degrees/marks etc. and can tell you to what it corresponds in the U.K. You can also apply to it individually. You find details at :http://www.naric.org.uk/
It is essential that you get that, because even within the same country different universities have different marking scales.
Hope it's useful.