Hi there,
A PhD can be funded by RCUK (BBSRC, EPSRC, AHRC etc.) or charities (Welcome Trust, British Heart Foundation, Diabetes UK etc.).
Furthermore, supervisors themselves who have money in their grants to take on a new PhD student can support you. They can also help you look for funding opportunities as they may have more contacts and better experience.
However, as you are going to Oxford, there should be scholarships advertised by the university itself. As universities often have numerous obscure sources of funding which are not easy to know about. So make sure you reach out to the Finance Team.
If anything you can try studying your PhD part-time to work on the side and self-fund.
I hope I managed to help!
Best of luck,
Melanie
LSBU Rep