I think the 3’s in core APs (history, English) will be a problem, and you will need 5’s in all the remaining subjects. Law at UK universities, but esp Oxford is reading and writing intensive. You will be writing several papers a week, with several sources to read for each, and then presenting your work in a v small group (2-3 students plus prof) to discuss and defend your point of view. All this in an 8 week semester.
Getting an A in the course but a 3 on the exam doesn’t bode well for a high stakes exam based grading system. All those essays I mentioned above? they don’t count for your grade - its based largely on end of term exams.
Does this way of working appeal? Have you read the course description which will tell you what you’ll be studying for the next 3 years? Do any of the following texts sound interesting to you? have you read any?