I too am doubtful. With a 2:2 maybe at a lower tier (but not necessarily poorer) university, but you have to ask yourself what you're seeking to achieve. If you're looking to make up for your poor BA with an MA, the MA itself must be worth doing, and I question whether an MA from an institution which accepts you with a 3rd will do the job.
Times are hard for the graduates of 2009, especially in Finance related fields. The best (and even mediocre) employers now only entertain applications from those with significant experience (i.e. those made redundant from bankrupt companies), or graduates from the top institutions (Oxbridge, Imperial, LSE, UCL, Durham...etc).
Far be it for me to tell you what to do, but I would take a year out and try and secure 3 or 4 internships to build your CV. Good work experience is now one of the first things that employers look for - so it is on this area that you could now focus on to improve your chances of getting a job, rather than getting into more debt for a degree that won't do what you want it to.