Original post by ellie.rewWow, that's a very wide range! With such a range it's hard to pin down one uni with a particular strength, though KCL has David Carpenter for 13th century Britain and Cambridge has Rosamond McKitterick for Charlemagne and i think one of the London unis (maybe UCL?) has a higher than average (i.e. more than one) concentration of paleographers, though I know much less about that side of things.
In terms of medieval historiography, if you mean what I think you mean, you'll have plenty of that to do anyway, as I imagine you'll have to do a critical reading of basically every source you put into your dissertation (I had to write a report for my supervisor for each one e.g. style of writing, construction of text, political motivations/partisanship etc. etc.), so I don't think that will be much help in the decision making process!
Just a word of warning - if you're not very sure what you'd like to focus on, for the year at least, be warned that Oxbridge (and especially Cambridge) do want to know what the general thrust of your research will be when you're applying (although they are very flexible when you arrive, I doubt 13th cent. Britain to pre-Christian European religion would be a possible switch). Other programmes seem to offer more flexibility.
I'm actually working in a library at the moment, paying off the debts (these masters aren't cheap kids!) and applying for PhD next year in London and Oxford.
I have heard nothing but good things about Medieval Studies at York!
Bear in mind that with boundaries between disciplines so blurred now, the choice of History vs Studies is often more about the structure of the actual degree (e.g. in Oxford Studies is 9 months vs History is 11 months, with the summer to finish your dissertation). I know a lot of Medieval history people who did very interdisciplinary/culturaly stuff, along with a few medieval studies people who took nearly all the same classes as I did and would have had no problem being in the history course. Of course if you want to study Medieval High German literature or Urban communes in 13th century Italy, then your choice is clear but there's lots of room for overlap. (N.B. if you can't tell which topic goes with which course, then it's time to worry!)
I really loved oxford, and I really hope I get funding to go back next year. The libraries are fantastic (even have really obscure foreign language books and journals) and of course have a huge amount of medieval manuscripts, which you can just order up to look at whenever you like! Also having a practical paleography class with an original magna carta is amazing! You will also have a college and a college library, which are usually quite well stocked and tend to just buy you any book they don't already have (which again is amazing). You get really high level access with top scholars in every field, not just your supervisor, but also with the seminars (which always have drinks and a chat either before or after), where visiting speakers come nearly every week, from most of the universities mentioned above and from lots more too.
The downside is I think the stress and workload, but I think that's every master's, not just Oxford. It's a big step up from undergrad, not just in quality but in quantity too. It's very easy to feel overwhelmed, stressed and lonely, but again I think this is probably a universal and Oxford has so much going on (seminars, concerts, socials, balls, dinners etc etc) that it's never hard to find something to do if work's getting too much. Keeping up with it is exhausting though, I have much more free time with my full-time job now than I did last year!
If there's any more questions though, just ask!