Hi
i only had GCSE grade C in Physics....i managed to pass all 14 exams first time with my lowest mark 86% i think off the top of my head....so in answer to your question...YES! its possible
however obv a more complex understanding of the subject WILL make it so much easier and simpler to comprehend. I found myself having to spend many extra hours compared to others to get my level of knowledge upto scratch!
As regards difficult subject...it depends how you approach them - if you are simply doing it from the books then for me Air Law is so boring i find it impossible to read and take in! haha
If however your doing a lot of feedback - ie Bristol or other means. I would have to agree that Gen nav and Met are very challenging.
(airlaw is much easier doing quesitons!!!)
adam