It awes me to see how
You already used a similar phrase in your first paragraph. Try not to repeat things like this too close together.
in a sensible region as the brain
I don't think "sensible" is the right word here . . .
I have suffered a number of setbacks during my preparation of my 4A levels. There were times when I could not cope with the workload or the speed with which some chapters were discussed. However I've never let my head down and each time I had the sensation that I was lagging behind the rest of the class I redoubled my efforts to bring myself back on level terms with my friends. My perseverance has allowed me to spend all my seven years in secondary school in the best class and I am certain that I can repeat this performance at university level.
This paragraph is unnecessary, as your transcript should tell the admissions officers most of this anyway. Also, shorter statements are better than longer ones, given how many they have to plow through.
Hmmmm . . . I see. The rest of your paragraphs are also pretty much irrelevant to your application, and read like a summary of your resume. I'm guessing you probably listed most of this elsewhere on your application, but even if you didn't, none of it really has any bearing on your ability to be a good medical student. I'd replace the second half of your essay with a discussion of what you hope to accomplish in the medical field.