After grammar and spelling, the next problem that needs be checked is transition. Read your essay. Go through it from end to end, and check to see if your essay flows smoothly. Does each sentence flow smoothly to the next? Does each paragraph flow logically to the next? Each statement should be connected or somehow related to the one before it, not thrown randomly together. Next, limit the use of "I" in the beginning of most sentences as it is already obvious that the essay is a piece written by an individual.
In some ways you are very lucky because your experience of high school, hobbies and life experience will already be different from many UK/ home students so you should take advantage of this in your personal statement. But you also need to make 2 things very clear. Firstly, why do you want to study in the UK and secondly, you need to show that your English is of a good standard (usually IELTS 6ǌ or above). It is no good having IELTS 6Ǒ if you personal statement is full of grammar and spelling mistakes. But DO NOT pay for someone to write your personal statement for you on one of the many websites offering this service. If you have IELTS 6Ǒ, you do not have perfect native speaker style English and universities may reject your application if they suspect it is not your writing.