There is space for 4,000 characters (this includes spaces) or 47 lines of text (this includes blank lines). Guidance is available from UCAS on what to include and how to complete the reference. If you are applying as an individual then you will have to input the reference on their behalf - in other words you will paste in a document they have written. If you are applying via your school they will be able to add your reference automatically. The reference should be written in English.
Your reference should not be completed by: If you are currently studying, or have recently left school or college, you should ask your head teacher, principal or an appropriate teacher or tutor to provide a reference. Your referee should know you well enough to write about you and to comment on your suitability for higher education. The reference is an essential part of your UCAS application, where someone writes an account of your suitability for study on your behalf.