Not sure how to support her while she's holding back on information. An added point is that our relationship is not great due to us spending very little time together as she's more interested in going out clubbing. I'm so worried that she will lose all focus with taking a year out
I think you're going to have to live with this & ride it out. If she's a 3rd year, she's very much an adult. And I don't know if there's a back story about your relationship with your daughter, but really - do you expect her to treat you like a friend? She's your daughter. If she's more interested in going out with her own friends then I'm sorry, but that's absolutely normal. Were you still spending most of your time with your mother at age 21 or so?
If what you're worried about is her work ethic & her results, that is a different thing, but again - she's an adult. It's tough to watch, but you have to let them find their own feet and make their own mistakes. When I think of some of the things I did at university age 21
My parents didn't expect to have a say, although they would listen, and advise - but only after I"d talked to them & told them what I was thinking about. Although I was very independent - I'd worked away from home at the age of 17, and then to university at just 18.
If you want to help her, start collecting information - but not about her, but the situation re fees, maintenance loan, and so on. Help her gather the information about the latest point at which she can withdraw without penalty on her transcript. If she's in 3rd year now, it may be too late for this term/semester. She might be well advised to stick it out until CHristmas, and then defer for a year.
You could also advise her that a chat with her Personal Tutor (as academics we advise in a pastoral as well as academic role) about her options.
Instead of being hurt yourself (this really isn'y about you) that she doesn't spend time with you, maybe start to probe, gently delicately subtly, why she feels she needs to defer 3rd year.
And, speaking as an academic, if she's not ready for the 3rd year workload then it's a good thing to defer. I think students should take the time they need - if I ruled the world, every intending undergraduate would be required to take a gap year & do something else useful. So a gap year now is not always a bad thing or something to worry about.