Breaking into ER from a non-traditional background

Fellow monkeys,

I’m an engineer from a non-traditional background - government/non-profit/education, considering a UK MBA (Oxbridge) to pivot into ER. A little bit about me:

UG performance is below par but from a respectable UK university (lower second class from a Russell Group university). FWIW, I’m working on an alternative transcript (got two courses completed with As). Based on my practice tests, I’m expecting to obtain a decent GMAT score (720+ with quant at least 47).

If I get admitted, how can I make the most my time before matriculation? Would completing CFA level I be advisable? Or should I pursue a certificate in finance from an extension school?

I’m targeting BBs as I’d need a visa to work in the UK and they’re most likely to sponsor. Am I right in thinking that I have a shot at this? Would I even be considered for this or any other role in finance because of my background? Or am I better off pursuing other industries?

Looking forward to your responses.