I'm in Christina Barratt! I moved back into college in 6th week last term and luckily a girl was moving out, so I took her room.
I lived in a one-bedroomed flat with my boyfriend (who I had been in a relationship with for over a year before we moved in together - though we broke up in Michaelmas and that's why I went back into College) - it was just off Cowley Rd and I can PM you street name if you like, because there are houses on that street and it's a lovely quiet street and I would recommend the area. As there were only two of us, we hunted together. Please don't panic - it was hard finding 1/2 bedroom places when I was looking last year, but you don't need to worry, as there are always bigger places available well into February! The only incentive for looking earlier is to find the very nicest or cheapest houses, IMHO. I strongly recommend staying on the room ballot and trying to get a College room - you may not end up on-site but I think you stand a fair chance of getting an off-site room (most of these are down Iffley Rd).
And as for getting a CBB room in third year: if you get a Scholarship or Exhibition after your Prelims, you're virtually guaranteed to be high enough on the room ballot; if not, it's all down to luck. You're welcome in my room any time though. I can PM you the number. This is a serious comment - I haven't seen you since Freshers' Week, I don't think! I'd like to catch up with you!