It makes no difference whatsoever. Ok it feels like crap at the time but in the grand scheme it's a minor setback.
Your training doesn't stop at the end of first or final year. Formal training stops when you are either board certified or obtain your CCT. Either way, failure isn't not passing an MBBS, it's not doing the best of your abilities for your patients later on.
I’ve seen mediocre doctors sail through medica school and good doctors who had to retake at least one exam. So focus on the end game, MBBS is just the beginning
David Yeo, Consultant at University Hospital Birmingham NHS Foundation Trust
Source: Quora Digest