Career Dilemma - Would Appreciate Advice ASAP pls help!!

Hi all!

OK so I'm currently unemployed, because I have been studying for GMAT and wanted to make a career switch into banking (ideally) or consultancy via getting into finance masters in top targeted schools in UK. Still unsure what exactly I would like to do in banking (hence want to do masters), but very inclined to IB, M&A advisory... 

I did go to good uni in UK (not finance or econ but related) and had a full time job after it in a really good company for a year and half but again non finance job at all. So I'm very sceptical of me getting in top targeted schools since I don't have experience in finance, and I wanted to increase my chances by applying to finance jobs. So just now I got 1 offer which is in big 4 in audit, however I'm in huge dilemma should I accept it since it's not really want I wanted and not sure if it would advance that much my application. Also, it will take so much of my time from GMAT preparation, if not all, since I have to study for ACCA. 

But on the other side, it's really good company and having it on CV is beneficial.
Also, I'm scared to accept it - what if there is some better offer that is really related to the field I want to study? I would even accept low paying internship in a small firm that is in finance or banking. And I have been only applying for 1 month.

But at the same time I'm scared to decline it - will this only be my last chance? What if I don't get in any targeted schools and can't land any job in finance, not even accounting...

Since I'm quite new to the industry really would appreciate any advice and help! I need to decide in few days!!