I've heard that the cohort is extremely competitive and some of the people are so determined to get into med that they cut themselves off socially and even take sneak peeks at other peoples lab reports for their own gain
You'll get people like that in any course. They're usually the people who sit in the front row and go up to the lecturer after EVERY lecture to clarify half a dozen completely irrelevant points.
Based on my experience over the degree it's a mixed bag. It's competitive but people are aware that helping somebody isn't going to severely disadvantage you. Everyone can (theoretically) get H1s and GPA is only part of the medicine consideration. Most people are sociable in lectures/around uni but don't go to events (other than the major ones, like the ball) so it's not a collection of shutins who only care about marks.
And as for PG med statistics, based on the estimates of students applying the
maximum amount of biomed students in the MD is 40%. Nobody knows the real number and we won't until...mid January probably. Mark Hargreaves will probably tell some of us if we ask him but they've been kinda quiet about it