The person you choose to look over your statement should be checking everything. Along with grammar and spelling errors they should check the tone of the paper, the flow of the paper, and the overall style of the paper. So, it makes sense that the person you choose to look over your admission essay should be well tuned in writing. Additionally, they should also be able to let you know if there is anything they feel you should omit or add. Once you have made the changes they recommend, then you should have them re_read your personal statement to ensure quality. If you want to be ultra_safe, then have yet another set of fresh eyeballs look over your revised personal statement.
Your UCAS personal statement must demonstrate: Why you would like to study your chosen subject _ What has influenced your choice of subject _ How studying your chosen course will progress your intended career _ That you are prepared for and will be able to cope with university life _ Attending university will develop you as an individual _ Your achievements in life both academic and extra_curricular _ How any work experience you have conducted has improved you as a person _ That you are a person with a range of interests