Oxford College Application Change?

It is only a college preference. The application process can shuffle you around between colleges at several stages. If you are fortunate to be made an offer it could come from a different college.
I've not heard of the one week period for changing college preference, although it may still be possible to do so. Best advice is to stay with Wadham and begin interview prepping. Oxford undergrads always develop a close loyalty to their college whichever it might be.

Chill! You may end up at one of those colleges, or neither. Hope you get in somewhere! Me, I like Univ more than Wadham, but that's cos my uncle went to Univ way back, and also cos having blue hair and pretending to be Northern (Wadham) seems kinda over. I'm not at either of those colleges. I'm at a super unfash college (no tourists!) which suits me just fine.

Hi! I recently applied to Wadham College but I’m still torn between that and Univ… my UCAS has already been sent off, but I think there is a one week period where you can request to change your college preference.
Univ is quite popular and gets like ~800 applications (so more competitive), whereas Wadham is less at ~500…. Would it be silly for me to change to Univ and hope that I get pooled into a college I like or somehow Wadham, or just stick with Wadham? It sounds silly but I’m just genuinely so torn and I wish there was a way to indicate 2nd preferences

For Law, it's about 40% offers at other colleges. I got into my target college, but it's not one of the most trendy ones.

I didn't apply to Magdalen. As you know, at the early stage, each law application is handled by the Faculty, not by any of the colleges. The apps go to colleges later if not rejected in the first sift. I'm just a second year law student, and I don't know how the system works in detail, but it seems that about four out of ten people who get in for law get in at a college they didn't apply to. I suppose this may perhaps result from law being a popular subject to apply for, so people get moved around to fill up the places at all the colleges, but I don't know.
I got in at my choice of college, and was only interviewed by that college, but other people get interviews at two (or more?) colleges. I think that the idea is to make sure that the people judged to be the top ten percent or so of the applicants get places at one college or another.
I repeat the point that everyone makes: once you're in, you tend to like your college, whichever college it is. I think that people who don't like their college might be people who don't much like Oxford in general. Some people get here and don't like it. Some drop out. Some stay but don't enjoy it. I like it here and so do my mates here. I like the (hard) work, I like the active social life, the sports and hobbies, and I like being in this amazing city surrounded by history. The tourists can be a drag, but you can mostly ignore them, especially if your college isn't on the tourist track.
Good luck!

I meant did you get an email from the college you applied to in October as a welcome email or only drink the faculty?