Just got a reply email from my 1st choice and...theyre OK!
they are happy for me to send of additional info via email re: my references and amend my dates between now and november.
I will wait for UCAS to change my tiny 1 letter error first then submit my supporting info?
Downside: they want my transcript (which for my 1st 3 years is ok, last year was a nightmare due to way too many extenuating circumstances which I need to verify with my uni based referees) - I did an undergrad masters btw which is why the 4th year is irritating. I will say however that despite my final year mishaps, my overall grade was Merit / 2:1 for Masters