anowl, my apologies, I am with you now. I have no useful information for you there. My only observation would be that she has applied to Christ Church, so if she is able enough to get into Oxford, they're going to want first dibs.
Number81, I'd never thought of it like that before, with respect to character. It's a good point. From my experience though, they're not looking for rounded characters, with grit, discipline, and a diligent attitude. They're looking for academically capable individuals who are going to thrive in the tutorial system.
For extra-curricular activities, it's excellent that he has other things to focus on so he's not stressing out about exams, but has useful outlets to keep him emotionally (and mentally!) sound. But I should point out (apologies if you knew this already), that Oxbridge does not care at all about extracurricular activities. You're right, it is a very competitive environment, but only as far as you have to be bright to make it through. I've said this before, possibly in another thread, but my tutor laughed at the idea that they would care if a candidate has gold Duke of Edinburgh, or is grade 8 cello, or volunteers. It's important for your son as a person he has these things (life can't be all books and study!), but as a candidate it is not relevant.
I don't know if the above has eased your mind, or not!