Oxford is a wierd place for going out. You've got a mix of Oxford Uni types, Overseas students, Brookes Students and then locals from Oxford and the villages around Oxford.
If you are talking about Brookes girls ... I think Sam from Big Brother probably represents them quite well. Lots of rich daddys girls straight from school, generally with a bit of a chip on their shoulder and interest include shopping, getting hammered, sleeping with a rugby or rowing lad, and generally not wearing much! On the whole prettier than average .. but don't delve too far beneath the surface! While I was there dress code was generally as little clothing as possible, (Sam from BB was known as "Hot pants girl" as she only ever seemed to go out in tiny hot pants and a bikini top). Unless things have changed since I have left (and probably have) they perhaps don't fully fit into the OPs description.
(PS - This is my opinion as a Brookes graduate - and one month away from marrying a Brookes girl - there are always exceptions to every rule
Oxford Uni girls generally stay within their own circles unless they venture up to the Brookes SU to as one Oxford girl put it to me "Pick up some fit, rich and thick guy from Brookes" ... amusing considering what we'd been doing a few moments before. Unlikely to fit the OPs description.
If you go out in Oxford outside of term time (or just to Park End on a weekend generally) then you are talking about a totally different type of girl again. Probably closer to the fake tan, ladette type the OP was talking about - but not all of them are like that by any means.
Particularly in Oxford, it does make a huge difference where you go out and actually just as importantly - when you go out (week night, term time or not etc). I'd suggest going out to different places at different times until you meet someone more to your taste! Believe it or not there are plenty of perfectly lovely British girls out there.