An additional note: the Faculty of Law at Oxford operates a semi-centralised admissions system. The initial sift of applicants is carried out by the Faculty. Those applications which are not rejected at that stage are then sent to the each applicant's target college. Some applications may be sent to more than one college. For example, the application of a mature applicant who has not applied to Harris Manchester College (which specialises in admitting and teaching mature students) may be sent to that college. The aim is to ensure that the top ten to twelve percent of applicants obtain an offer at one college or another, whether that was the applicant's target college or another college. A few (very good) applicants may be given open offers - those applicants will be allocated to a college after the A level results are published (because some offer holders will not achieve the grades required to take up the place at Oxford).
There are no bad colleges at Oxford (or at Cambridge)! Colleges differ in endowment, in size, in architecture, in state vs private school balance, and in atmosphere, but at the end of the course you graduate as BA (Oxon) or BA (Cantab), as the case may be. You can opt to become an MA a bit later on - the Oxbridge MA is a rank within the university, which confers voting rights in university elections.
An Oxbridge degree can open many interesting pathways in the world of work, as can a degree from any of the leading universities in the UK (and of course many pathways can be explored without a degree, and with a nondescript degree from a non-shiny university). Is a place at Oxbridge worth striving for? I shall now enter Mandy Rice-Davies mode and say: yes it is. But don't fixate on one university. There are many excellent places to study.
Good luck!
Miss S Byng MA (Oxon)