You can't catch shingles from shingles but if you have never had chickenpox you can catch this from shingles which is particularly dangerous if you are less than 12 weeks pregnant apparently. Anyone who has had chickenpox can get shingles because it is basically the chickenpox virus that lies dormant in your system and then gets triggered to give you shingles. This can happen for loads of reasons such as stress etc, and obviously not everyone who has had chickenpox will get shingles triggered.
I work in a school and when I was 11 weeks pregnant one of my kids had shingles. I was obviously frantic but the NHS website and my midwife explained that it was probably very low risk for me as I have had both chickenpox as a child and also shingles a couple of years ago. Obviously if you don't HAVE to work with this person then I would steer clear if at all possible, as it's better to be safe than sorry, but if you have already had chickenpox it should be fairly low risk, and you could get shingles at any time anyway as it is already dormant inside you.
And on the other hand, shingles can make you feel bloody awful so does this poor girl really want to go to work anyway??!!!