This does not answer your specific question, but if you want to see how head injuries are generally dealt with by the UK CAA you might want to look at this..
https://www.caa.co.uk/WorkArea/Downl...?id=4294973901
You have not said exactly what the surgery was for, nor for how long were were unconscious, but using the term "in a coma" suggests a considerable amount of time. If it was more than 24 hours, it seems to me from the published guidance that that alone may limit you to a long term OML.