Blue Tits

The old nest box in our garden did not appear to get any interest from tits this year so when we thought to take it down and replace it with a new one, we were surprised to find a female blue tit on it sitting on eggs. However, on keeping a eye on it over the last day and a half, there is no male going in and out feeding her. It looks like the male have abandoned her or died. Will the female survive, will she manage to raise the chicks on her own, and what can we do to provide her with an extra food supply for her and her chicks when and if they hatch?