I don't know what's best to encourage. She has had a job in a supermarket since she was 16, she is now 19 (had to resit a year in a levels) and still has her job of course. It's only 10 hours a week currently but if she does a store move (which they can try and accommodate, but isn't always possible anyway) she is probably looking at no where near a contract that low. Most likely she won't be able to move anyway and will have to just leave and find a new job.
She is lucky in that her grandparents are covering her full rent cost. She will then have her full loan £8k? To just live on. She will need to pay bills and her car will be a lot (she is renting a small flat and this is what my grandparents will pay) I know most will not agree with not going into student accommodations but it's right for her.
So she has what £666 a month to pay for everything else which is plenty. She is very sensible with money, so I don't know if I should be encouraging her to focus on her studies or encouraging her to keep earning her own money, you know?