What chance do I have to getting anywhere in finance?

I was on target for a 1st in physics at Oxbridge but one term got beaten up, got into a negative headspace, transferred uni, was unfocused and finished with a low 2:1 from a uni just outside target.
I'm now 30, have a good sales track record, am totally focused and need to decide if it's worth spending time chasing the finance dream.

I know finance favours young grads, but assuming I am able to prove my ability in field, there's got to be some avenue available, some room for manoeuvre?

Audit to TS to something possible? Or is am I pushing sht up a hill?