I have nc from a name I have used on this thread, as details are personal.
Martorana has some points.
My DD applied and got an interview at Cambridge. She didnt get in.
She is from a state comprehensive, which I am not sure has ever had students get into Oxbridge. They may do, but it certainly isnt advertised. I even had a problem with the Head and her year yead, in shivving up whatever they had to do their end to support the application. If I had not gone in and kicked up a bit of a fuss, the application woudl not have got there in time. My DD knew that there was one other pupil applying too, so we sort of worked together. The Year Head had other things going on in his teaching life and basicaly wanted to do all the uni applications together or something, and I dont think they even realised the early deadline.
But my other main point is this. Together with them not really having a clue, I realised that they were completely unable to help us two parents with any knowledge about our applications whatsoever.
I had to do what I could via googling for tips[I dont knwo anyone personally well enough to have asked for help with the application.
As I said she didnt get in. And I realise that not a lot do, even with an interview.
But I do think we would have had a lot more help from a school that regularly had pupils there. Not to mention tips I could have picked up from other parents.