Hi Charlotte,
You know what's delicious for breakfast (I think anyway)? Vegemite and avocado on toast! It's really filling and will keep you going through til your next meal or snack time.
For lunch you could try making a wrap? Fill one with corn, baby spinach leaves, grated carrot, grated beetroot, sliced mushroom, sliced cucumber, sliced tomato and avocado. The shops even have these great spinach wraps which are green in colour and taste really good.
Dinner, a nice pasta with vegetables and tomato sauce?
That's really cool that you're trying to go vegan for a week. Grab some more recipes here:
http://www.unleashed.org.au/change_the_world/go_veg/vegan_recipes.php
Make sure you offer to help mum and dad with the shopping and cooking for this week, otherwise they may not want to cook "special" meals for you. You may even have to share your delicious wraps with them
Have a great week and make sure you tell us all how you went!!