I was fully funded, but got a bank loan when my PhD overran. HSBC gave me a 'professional studies loan'. The problem is, when I applied (rules may have changed now), they were only interested in giving loans to the traditional professions.....denistry, medicine, law etc. for vocational courses, but if the PhD fell in those fields they seemed okay about it too.
They may have broadened the fields of study now, but they may also be stricter due to the ole credit crunch. Nevertheless, check them out.