I agree bestman, however if their Civil wedding was not valid because he was married, then the following questions could save her the cost.

Was he divorced (fully) at time of Church Ceremony. If answer is No (still married) then No the wedding is not Valid.

If the answer to the above is Yes, then was the Church Ceremony a Fully licenced wedding or a Blessing of the invalid civil wedding. If the answer this is it was Blessing then No the wedding is not valid.

So if he was divorced and the church wedding was a full wedding then chances are it would be valid, but given the history professional legal advise is advisable.

If however he was not divorced, no point wasting the money, it wouldn't be legal, and if it was only a blessing then again no point wasting the money as that is based on the illegal civil wedding when he was still married.