Well I still don't understand the no meat or fish!
The walking will help enormously.
Below I have listed the foods I suggest you either cut out or seriously reduce on a long term basis, not just over the next 15 days!
All cereals
Toast
Marmalade
spaghetti
noodles
bread
orange squash
All these are heavy in carbohydrates/sugar. For diabetics, all carbs are bad because they all turn to sugar once inside the system, some quicker than others. This doesn't mean you can't have any carbs, but you have to seriously reduce them and avoid the worst ones. The worst ones are bread, potatoes, pasta, rice, pastry and batter, plus some fruits. Sugary drinks like orange squash should be avoided. Milk is also full of lactose, which is sugar, so that should be taken in moderation, for example in tea or coffee.
Try a plain yogurt for breakfast with some berries thrown in - strawberries, raspberries or blueberries, but not many berries. I'm afraid you are going to have to make friends with salads and vegetables or you will starve. Presumably you can eat eggs? Boiled, fried, poached or any other way are good. If you simply cannot live without bread, then buy a heavily seeded sort, like Hovis Wholemeal 7 seeds, or Burgen, but only have one slice with a meal.
I also suggest you buy a home testing kit and testing strips as soon as possible. Having one of these will help you control your blood sugar levels, and is the only way you will learn just what food does to you. If you test before you eat, then 2 hours after your fist bite, you will see a rise in levels. It is these rises that will cause you problems. The aim is to keep these rises as flat as you can. You won't do this if you eat too many carbs.
Remember, for us diabetics Carbs = Sugar.
Please have a good read round the forums. There is a lot of information on here, including food suggestions, recipes and so on. Come back any time and ask as many questions as you wish. Good luck and let us know how you go on.