As you all ready have an undergrad degree have you checked out the funding situation for another same level course?
I know BA students do get an NHS bursary, but I think they usually receive student loans too, which you may not be eligible for again. What about the tuition fee aspect too?For the MA course, you do get a bursary and tuition fees paid, for definite. (I am due to start the MA in Sept).
The other consideration is how to explain to employers that you have two same level degrees, rather than a higher level social work qualification. Could you ask for feedback as to why you were rejected for the MA course? It may help you decide whether to wait a year and gain more experience first (which may also be beneficial when going for post-qualification employment) and then re-apply, or whether to just go and do the BA immediately. Either way, you would still qualify at the same time!