Thanks for all the comments. I know she's only 12, but being from a fairly low level of education, pulled myself up by my boot-strings kind of background, I'm struggling to know the right way to approach it even at this early stage. I've encouraged her to think of other universities as well, explained the 'red brick' universities as best I can. I didn't think to say that different universities offer different strengths, but that gives me another line of discussion for her.
I've said that she will have to work hard and that they only take the best of the best. She knows it's a tricky place to get into as her friend's brother, who is the loveliest boy, has recently been accepted for interview, but blew it and is now out of the running (his words...didn't realise they let them know immediately).
DD is in state education, not private. She is passionate about English. She's 'chosen' her options already and has included Latin and French for languages, history over geography and art over dance.
I am factoring in that she is young, but I know how easy it is to squash someone's dreams when they are young and change their whole life trajectory. I don't want to be responsible for that, but I conversely don't want to encourage her towards something she's not able to achieve. In that light, I've asked her old primary school teacher (I work with her) for advice. She's said that she'll check with her DH (dd's form tutor) what we should do. She will tell me if it was waste of time I'm sure, or she just won't come back to me. In addition, I'll ask the teachers at the next parents' evening whether it's realistic (if I can talk DD out of coming with us!).
The subject doesn't come up too often in the house but she has mentioned it before and we've said that's great and told her to consider Durham and Lancaster, cos her dad works oop north most of the time and it'd be practical :) I was just so shocked that she'd told her friends. It makes it seem much more 'real' if you know what I mean.
I did wonder whether I'd just get shot down for being unrealistic, told she's too young, etc, but most people have said to encourage her, so I think we'll step back, find out what we can about it all in the background and just encourage her in her pursuit of a great education, wherever that may end up.