I'm in exactly the same boat. I knew I was applying kind of late (I was expecting to work abroad for a year but my work visa fell through) and so wouldn't be able to get a traineeship for the GDL this year, but because there's there's so much confusing, outdated information out there on various law careers advice sites cheerfully promising that its easy to get a Careers Development Loan to fund the GDL, and because I have no student debt so far (I did my BA abroad on a scholarship), I figured it wouldn't be a problem to take on a small debt for this year, and apply in the coming year for traineeships/scholarships that would take me through the LPC/BPTC. I also went in-person to Barclays and was assured that it should be no problem. Got my offer to study the GDL at Northumbria and phoned up the national careers service...and discovered that I'm kind of stuck.
So I'm also looking for any advice on how to fund this on my own without deferring. Surely there must be loan options out there that aren't exclusive to particular institutions (e.g. UoL's agreement with Metrogate, BBP's with Investec)?