As Mrs Weasley says: "We'll manage."
‘That lot won’t come cheap,’ said George, with a quick look at his parents. ‘Lockhart’s books are really expensive ...’
‘Well, we’ll manage,’ said Mrs Weasley, but she looked worried.
Chamber of Secrets - page 38 - Bloomsbury - chapter 4, At Flourish and Blotts
I think the Weasleys would expend every single option imaginable before applying for charity on Ron's behalf, and even then I don't think they would do it. Mr Weasley actually doesn't have a bad job; I think he gets paid adequately for his work as a government employee. However, with such a big family, a Galleon just doesn't stretch as far as it might elsewhere. The Weasleys just do not seem the type to ask for charity, IMO.
Furthermore, Ron, after receiving his Howler, knew better than to ask for a new wand:
‘Oh yeah, and get another Howler back,’ said Ron, stuffing the now hissing wand into his bag. ‘It’s your own fault your wand got snapped –’
Chamber of Secrets - page 74 - Bloomsbury - chapter 6, Gilderoy Lockhart
I don't think he dared to ask for a new wand. And if he didn't tell his parents his wand was broken, and apparently none of the Hogwarts staff did either, then I think the Weasleys might plausibly have not known Ron needed a new wand. He didn't go home for the Christmas holidays, so he could have managed to hide the status of his wand from his parents until the summer holidays.
There are two possible exceptions to this: One, it's possible Ron went home for the Easter holiday (I personally don't remember that he did, but I could be wrong), and 2) when Molly and Arthur Weasley came up to Hogwarts after Ginny was rescued from the Chamber of Secrets, perhaps they noticed Ron's broken wand, or Ron told them about it due to the backfiring memory charm incident with Gilderoy Lockhart.
J.K. Rowling doesn't tell us why the Hogwarts staff didn't notify the Weasleys about Ron's wand, so there's no way to answer this part of your question definitively. :)