Work notice (as she is doing) and leave on good terms, or it could come back and bite her on the bum.
Think most would just **** it of(f) anyway. Ring in sick or something. They can't with hold her money, and they can't give a bad reference. Believe me, i've done it loads of times.
Never had my paid stopped, and I've rarely worked notice, I generally either walk-out, or get escorted out. If you do it right they'll pay your notice and holidays too.