If I were you I would Google the name and add 'facebook' in the end.

So my search would be 'name of charity facebook'

Now if you don't find it in the search results, try to google something general like 'george facebook' and click on the google result that gets to all the profiles with that name. In this case it is  facebook.com/public/George-George . In that page there is a facebook search bar and you can search using that.