You do have to disclose your AS results. However, your PAT score is 100% more important. Oxford makes calls to interview on 2 things, your PAT score and your contextualised gcse score. If you look at the oxford physics admissions feedback report that they publish each year, they tell you the exact cutoff score you need in your PAT to get called for an interview. So you need to go all out for the PAT, and hope you reach the threshold.
I was called for an interview for oxford last year, it was due to my pat score and my contextualised gcse score.