I was looking at Warwicks website and they said:
While we try to build in a little flexibility to enable us to consider applicants who narrowly miss the conditions of their offer unfortunately it is impossible for this to be an exact science so if the course is full we have no alternative but to reject. If, when you receive your results you find that you have dropped by a grade on one subject it is recommended that you contact the undergraduate admissions office. At this stage we re-read your UCAS form (particularly your personal statement) and see whether you came to one of our open-days. We would sooner give a place to someone who has shown an interest in the way we teach law and the University and dropped a grade, than someone who has only just thought of us.
This is quite reassuring, but does anyone think they would have spaces if I were to drop a grade this year