£25 a week isn't too bad; a lot of students are on that kind of budget and manage well. You need to plan your meals for the week in advance and buy all the ingredients you need for the week. Every time I cook I make at least enough for 2 meals, it saves time and money. If you get basics range from tescos it should be fine.You do need to make sure you stick to your plan. Eating out can completely blow your budget!