- Remove the Courses below Mathematics
- Remove that gap between Sixth Form and write "A Levels" instead of "A-levels" (looks better, at least for me).
- Simply remove the word "Achievements", unnecessary to have it there (I'd also move this bulletpoint to the first: just to boost the first impression of who's looking at your resume)
- Also remove the bold from "A Levels" and "GCSE".
- About the last part: I'd get rid Certifications part altogether (not much of a selling point and takes space). Include Languages. Also I'd remove the simple listing of what societies you are member of (not much of a selling point and takes space). Instead, include "Interests". So last part should go like "Languages, Technical Skills, and Interests". The title of the section should also follow this. At the technical skills write "Basic Java/VBA programming".
- About the bulletpoints: they are OK but add trying more at the one which has only one (or get rid of it).
- Seems like a double space at "system using" at the "Implemented a more efficient stock control system" part. This could get your resume dinged.
Otherwise well done. You got quite a few interviews coming your way.