Hey, I just want to chime in as it's well and good waiting for the actual results to come in but I also have a hard time not thinking about the "worst case scenario", especially when I have some reason to fear it might actually happen. A mate of mine failed a module in undergrad - he had no extenuating circumstances (at least none that firms would accept - it was a module he was uncomfortable with, left it for too long, and cherry on top is his roommates threw a massive party the night before his exam (I know, some roommates...)), and had to resit.
He still got invited to various 1st / 2nd round interviews, and not with bad firms either - from memory it was places like Sidley, Addleshaw, Pinsents, RPC, NRF, Reed Smith.
So I think the majority of firms won't view that as a deal-breaker, it will simply be a minus on your CV that you'll have to overcome by impressimg them in other ways. Very few firms have absolute first / high 2.1 requirements for all modules, I'd say probably only the elite, small cohort US firms like S&C, Davis Polk, Skadden, etc. (though Sidley apparently not). UK firms will likely be more forgiving, especially SC and below. So I'd recommend taking your chances with them if you do end up failing this module, and if you'd had your heart set on one of these US firms, well just remember it's VERY commom to go from UK (even non-MC / SC) to US firm once you're in practice, especially in a high-demand area (like corp, finance, PE / funds, DR, etc.).
So best of luck with all your exams, and now go enjoy the summer in the knowledge that whatever may happen it won't destroy your legal career in the long (or even short) run!
