No it's not to late to state a garden this year. If you want to start you seeds inside you still can, but you can also go to a local greenhouse, home improvement store, or some stores (like Wal-mart or K-mart) & buy starter plants to plant. Here we plant our garden around Mother's Day, eventhough my dad always told me Memorial Day weekend is when you plant. But I haven't had issues with frost after Mother's Day & if there is a chance I just put a blanket over my plants to protect them.
Years ago I removed bushes from an area & my tomatoes did really well there! It was in a front flower bed of the rental we were living at... the cherry tomatoe plants actually grew up to the pourch roof & were loaded w/ little tomatoes.
As to keeping the critters out - you can find "chicken" wire or small holed garden fence and metal poles at most home improvement stores. If you are worried about rabbits, try to dig a trench & put about 6-12 in of the fence underground since they like to dig to get into things. They also sell repelant chemicals you can spray on your plants, but personnaly I'm not sure about putting chemicals on my plants that produce my food.
We are currently trying to figure out where we are going to put a small garden this year, so actually you are one step ahead of me this year - you know where you want to put it.
Also, my kids love helping w/ the garden & picking their dinner. It is cool to teach them, but I don't force them to help like my parents did us... if they don't want to do it - oh well, maybe tomorrow.
Good luck!