Well done to her for the offer! Should give her confidence for the next two interviews :)
DD1's school have been very helpful with the process - several pshe lessons; a parents' evening (that I didn't go to - figured I'd learnt enough here, lol!); they get recent old girls in to talk about their courses; they produce a comprehensive booklet going through it all, with advice from girls as well as teachers, and examples of personal statements; everyone gets a UCAS mentor. Probably more that I've forgotten about.
But I don't think there was very much at all on what or where - although I expect if you wanted that sort of advice, there would have been people to talk to about it.
And she's applying for Classics and her Classics teacher didn't know anything about the Oxford Classics aptitude test, which fortunately was funny because dd had read loads about it and found practice papers, but could have been annoying.
There's a local schools-business partnership organisation that does things like arrange work experience, and last week they put on an Oxbridge interview day. And I don't know who organises it, but some of the local schools distribute a list of teachers who are happy to do mock interviews if asked. So stuff like that is clearly great.