Omg? Do you not have laws against that kind of thing in your country, or is she just like, really, really stupid?
It's possible they won't try to contact the referee, but even so, I'm sure they do have people who can spot fake references, and if she was stupid enough to do this in the first place, she's probably stupid enough to have not written her reference well enough to hide that it is fake. If she gets caught ucas will probably alert the police.
Tell her to withdraw her application and do it again properly, with a real reference, before it's too late.