Hi, I don't know anything about your situation specifically (I'd have thought being a British citizen - presumably you're dual Canadian/British? - ought to count for something but might be wrong). However, I know someone who is an advisor on this kind of thing at a London university. Obviously that isn't your uni, but wondering if perhaps either Coventry or Reading has someone similar? (She's not a student herself - it's a full-time job for her to advise on immigration/visa/residence issues).
Initially, asking your student union might be an idea - I know mine is supposed to be able to advise on this kind of thing, and if not, to advise who would know.
Good luck!