You can type your personal statement in the online application form (3,000-character limit, including spaces) or upload it as a separate document. If you upload your personal statement, you can go over 3,000 characters but it cannot be longer than two sides of A4 paper (size 12 font and single spaced).
You should consider the following questions when writing your personal statement
Why do you want to undertake the programme or research?
What are your academic interests?
Why do you wish to study at UCL?
What educational experience do you have?
Do you have any relevant work experience?
Have you completed any extracurricular or voluntary activities relevant to the programme?
What are your career aspirations?