Hello there. To a certain extent it depends on... your daughters age, where she is going, what you want to finance, and whether or not you want her to earn some money through work for basic or leaisure stuff.It's a knotty one, this further and higher education lark. It's not just about academic learning, it's also got that whole social learning thing thrown in. So, to engage in a healthy social life you normally have to have a bit of cash in your hand. A social life isn't always about clubbing and drinking, perhaps your daughter might want to try out some new hobbies / sports what ever. College / University is usually a really good place to do all this stuff for the first time, so many opportunities that people rarely get to do all the stuff they want to. So maybe throw in anything from £10 to £30 a week, depending on what you can afford of course.
If you want her to eat healthy food you will need to be giving her at least £30 a week for that, but don't be too surprised if a lot of it goes on take away food. Then perhaps another £5 towards electricity etc.. on the basis that she can make some compromises on her diet and leisure to pay the required balance.
As to her working for extra income... it's a good way of getting her to learn about life in general, but it's also a good way of A) getting earning a basic living in the way of studying and B) introducing her to overtime, full time work, money in your pocket now..". perhaps this is better than going to lectures.. I'll buy a car.." kind of thinking.
You know your daughter best, you might be able to guess how responsible she'll be. Talk to her about it.Perhaps talk to the college welfare people, see what they think. What's the goal of going to college? Keep that in the front of your mind all the time. I saw several people drop out of university because they simply couldn't afford it, or they found it too tough to cope. I bet they learnt about how life really is. Didn't help their academic careers at all though.
Good luck, to both of you.
Paul