Depends on the sort of charity it is, but there are loads of funding organisations looking to donate money to worthy causes, particularly if they benefit certain sectors of the community. Your local town council, or the County Council website, is a good place to start, particularly if you want to fund projects rather than running costs.
We run a bi-monthly quiz, we charge £2.50 a head and people bring their own food and drink, and we have a tombola during the event as well. Make sure that if you are running raffles rather than tombolas, you have the appropriate licence....