Oh, well it probably changes the situation a bit if there is a summer programme you want to attend rather than trying to get over here sooner just for the sake of it, although I'm not sure how exactly you would go about it. Is the programme part of your course or for credit?
The thing about the prospective student visa is that it seems to be meant for people who have not chosen a course yet, but it sounds like you have already chosen one. I don't know if that might pose a problem if you try to apply for it.
I can't really give any advice as the whole Tier 4/student route situation has changed in the 2 years since I applied for mine and this situation seems a bit tricky.
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Is there an International Student Office at your Uni? Perhaps they might be able to give you some advice. Hopefully this will be seen by someone who knows a bit more about it. Sorry I can't really be of any more help than that!
But good luck and congrats on getting into grad school!
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