Hi Serin, yes, ds is in self catered accommodation. That (and what he earns in the holidays - which, tbh, often also gets spent in the holidays, he's not a great saver....) covers all his food, travel (and his girlfriend is in a different City, so that adds to the 'around town' travel), toiletries, phone contract, and socialising. He's become a canny shopper. 
Don't get me wrong, I sent him back after each holiday with a bag of toothpastes, shampoos, shower gels, and a box with quite a few tins in to help him on his way, but, week by week, he manages fine.
Before he started, I asked my 2 nieces what they spend on food + bits each week and they both said "under £20 although the boys tend to eat more", which is why we plumped for £30 to allow for travel and phone, etc on top.
titchy - yes, that's why I said some will pay more, some less, etc - it's a wide variation if you read all these threads, that's why I was wondering why OP had gone for that specific amount, rather than the usual "How much do you give / do they need type question
. There will be those who get less than we do (although of course, that will be because their incomes are higher) but there are also bursaries and grants and other support out there for lower income families and also for higher grade students.
There are so many factors, it's another 'how long is a piece of string' factor. I was just demonstrating that, if you haven't got £400 pm, then not to despair 