Butter Diabetes

I want a diet consisting mainly of vegetables and fruits and fish. How do I do that?
I am at risk for diabetes – is the story of my family – and for my own health I would change my diet. I am also overweight even though I am Exercise regularly for the past three years. The problem is that I have no idea how what I eat vegetables feel full time in one meal, and I do not know the cost in terms of time and money. I come from a bread and butter European family so my diet was mostly sandwiches. I am 18-year-old male, 6'0 ".
You eat vegetables, fruit and fish. Is it not rather obvious …?