ORS or Overseas Research Students Awards in most cases cover the difference between the tuition fee for a home (ie UK) postgraduate student and the rate charged by the institution to an international postgraduate student for the particular full-time research course being taken by the awardholder. Around 800 awards are made each year and between 60% and 70% of applicants are succesfull. You can get further details from the Universities UK web site. You need to be accepted by a university before applying. Your university will then provide you with help and advice on your application.