I have a place to study at McGill as an exchange student from Leeds University but funds will still be ridiculously tight. Student Finance means that whilst I still get my loans, they go in on the Leeds date which is a month later than my McGill start date. They do have exceptions for this (usually those studying at Australlian Universities etc as they have start dates even before McGill) but I just miss the date by about a week. I am glad that I get so much support as an exchange student, i.e still receiving my loan and travel grants, but all of this will have to be initially covered by me and then reimbursed, including flights, health insurance, visas and a month's living expenses. Leeds have also taken the step this year to take away my low-income bursary that I get from them, totalling £3,000.
So I think, as someone from a low income family who has had to/is still having to consider giving up a place at a top University which I earned through securing good first year grades (and beating many others academically), it is very difficult to study abroad even on an exchange program.