I had a 2.2 from my bachelors, worked for a few years was able to self fund and masters before my PhD was fully funded. I had worked for five years in a profession related to my PhD before applying.
It might be possible to get funding if you have a decent reason for your third and can demonstrate that you're now capable of doing whatever it is you are applying to do but I'd imagine you'll have to really work hard to justify getting it. Even self-funding I had to submit a 2000 word personal statement and I think be interviewed alongside the standard application form (at a Russell Group university).