some universities/departments offer funding which is irrespective of nationality/residence, but this can be very competitive. you will have to browse the websites... the bill gates foundation offers funding for PhDs at Cambridge. If you are a woman, you could try the international federation of university women IFUW. Did you check out the wellcome trust? Having lived in the UK before, a key question is, do you have a work permit (or can you get one?) because if yes, you could try to combine partial funding with part-time work and living very cheaply, and if at some point funding runs out, you could work more until the financial situation eases up again. however if you can't work, you don't have that lifeline and so it is either fully funded or don't do the PhD, which will give you less options.