The same, nigh on impossible. Sorry, there's no nice way of saying it. By the MPhil do you mean the course at Ox? Well then pretty much 0%. The course is basically the non standard one..you really ought to have a good reason for taking it, usually something like "I need more language strengthening", "My degree wasn't focused in X area which is vital for my future research career". In general if you want to do real research the best way is an MA and then onto PhD.
Obviously I can only really pass on what I know from Ox and London...but yes the traditional route is the best one. The MPhil is not at all usual (you get more than twice the the usual time for a bit more workload basically...)
Depending on funding is naive, there are several really good upcoming scholars each year and only one/two get funding at MA stage. It's a serious problem, but understandably most departments are trying to allocate as much cash as possible to the PHD's since they're the valuable asset to a dept (yes, we don't matter....)
The situation sucks, especially for our subject.
My advice:
Work hard, that first matters even if it won't be a major decision maker. At the end of the day you need to produce good essays and have great references.
Read around your subject but have a good idea on where you want to go, pref from your penultimate year. This doesn't have to be REALLY specific, it's better if its not. But at least identify a language/time/author or genre as best you can.
Do save what you can, it's a ridiculous financial burden, but its worth it...it really is. Also, relax and enjoy your ug too.
EDIT: Just realised you're not even at Uni yet. Definitely calm down.