You can study what ever you want as long as the three periods are included. Over the three years you will do two British and two General papers, which are the ones in which have to fulfill the period requirements, but beyond that there are optional and further papers, as well as your thesis, which have no such restrictions, so if there is anything which grabs your attention in the British or General papers, you can pursue it as far as you want to.
Collegewise, I wouldn't worry too much about which tutor is at which college, as certainly beyond the first year, and in some colleges including the first year you'll have most of your tutes outside your college, depending on the papers you choose, as you'll always be taught by someone who specialises in that period. I advise you to choose on things like size, location, three years of accommodation etc... Hope that helps!