I am in the process of writing two applications for programmes in International Law and International Economic Law resepectively and seek help.

I graduated in 2014 with a 'good' 2:1 (65+) from a Russell Group University.
My grades at undergraduate varied however from 80 to 48, most of them were 2:1 grades.
Do the few poor grades I received preclude my application from being successful?
Also any guidance regarding personal statements would be welcome.
Thanks