The walk is about 15 mins but is pretty nice and scenic so not much hassle.
I lived in central campus and personally found Sherbourne to be more sociable than my own accom. It really just depends on your flatmates/surrounding flats, because that will decide whether you all have parties/go out to clubs as a flat. I wouldn't worry as you will find people to socialise with in any accommodation. The only place where you are really guaranteed a constantly active social life is rootes, but this accom isn't for everyone as from what I experienced it was very full on. But if you like going out often, it is definitely a great choice!