I have had this too, sitting down for a meal and a woman comes over and hands you a card and stands there whilst you read it.
Nobody in this country would have 3 children and be truely homeless. Chilcren would not be left on the streets to starve. However, she may be here illegally. In which case it's better that you report her and have the police / immigration called as at least then her children will be fed and given somewhere to stay.
I do often give people begging money or buy the big issue. The other day when it was so cold I felt sick going round the corner to Sainsburys there was a woman outside selling the big issue. She had a tiny baby (less than 3 months) in the buggy, wrapped up, but it must have been freezing. I didn't buy it from her as i thought having a baby there was a horrible attempt at making people feel bad for her and to buy a big issue out of guilt. As I said our welfare system ensures children do not go hungry, so there was no need for that baby to be there on such a frezzing, snowy day.