The odds of getting an account before you get here are practically zero unless you open a HSBC global account. I don't know exactly how it works, but someone else might have one and could tell you.
The banks here will require proof of address and sometimes some kind of letter from your university stating that you're a student. Sort of like a letter of introduction to show that you're legitimate.
Does your uni have an International Student Office or something of the kind? I found them to be very helpful when sorting this out last year, as well as this site.
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Also, you're not really going to be able to have much to choose from when getting an account. They usually stick you with the most basic account that will give you a debit card, since you will have no credit rating. That's what RBS gave me and I don't think there are even any charges because it's such a basic account.
From my own experience as well as my friends', RBS, Bank of Scotland, and Lloyds were the least amount of trouble to open an account with as a student, at least in Scotland. Barclays was a nightmare.
If you get all your ducks in a row when you get here, you could probably have an account in a week or so.