<p>If you have been invited for an interview it means you are past the first phase, although that doesn't mean much (90% are invited to take an interview) and you must make sure that you know whether you will be taking a test on your interview (most of the subjects have a test as part of the application process, that is held during the interview in your residential college in Oxford).</p>
<p>Info:
<a href="http://www.admissions.ox.ac.uk/interviews/%5B/url%5D">http://www.admissions.ox.ac.uk/interviews/</a> - interview info
<a href="http://www.admissions.ox.ac.uk/courses/subreq.shtml%5B/url%5D">http://www.admissions.ox.ac.uk/courses/subreq.shtml</a> - if you will be having test (just keep researching to find past papers)</p>