How much are people left with after paying rent at uni?

Is £400 actually enough for necessities like food and travel plus enjoyment plus saving money for holidays and necessities after graduation like a flat

Focus on necessities first, then saving for your future. Only then, if you have enough still left, should you be thinking about holidays and discretionary enjoyment spends. While I accept there are some people genuinely struggling, I think most peoples money problems these days comes from a simple inability to tell "need" from "want". I've lost count of the amount of students telling me they don't have enough money, but they always seem to be able to afford a Starbucks or a smartphone.

I will focus on the necessities but what about the rest of the money I have left? I need to prepare for a flat after graduation and money for enjoyment.