Surely 'well-educated' is different to 'well-informed'? 'Well-educated', for me, conjures up visions of a prep school and then a public school and then Oxford - something dependent on the education other people have provided for you. 'Well-informed', on the other hand, is possibly closer to what we're getting at here.
I'd say it varies very much for the individual. I'd expect a decent grasp of current affairs - or at least a good reason for why the individual is disinterested, if they know nothing about them. Anything else should surely come from their own personal interests - no point in learning about stuff that sounds intellectual just because it sounds good.