Preheat oven to 350 degrees. I'd also spray or butter your bread pan here just so you don't forget later.
In a medium bowl mix the flour, poppy seeds, baking powder, baking soda, and salt. I'd whisk this together to make sure its combined well.
In a seperate larger bowl mix the sugar, milk, vegetable oil (I subsititued for olive oil), eggs, lemon zest, lemon juice and vanilla. Mix well.
Pour the dry ingredients into the larger bowl with the liquid and mix. Mix well but don't mix too well. Somewhere in the middle is what you are looking for.
Pour into your bread pan and sit in the oven for 1 hour. 1 hour was perfect for me, came out nice and done in the center.
While the bread is cooking, take your powdered sugar and dump into a medium bowl. Then add a good helping of the lemon zest. Add the recommended lemon juice to the mixture, if its not to the consistency you'd like add more. I like the drizzle pretty runny so that it covers more ground.
Once the bread is out of the oven, drizzle the lemon mixture on the top, cut and serve. For some reason my bread didn't rise as well in the center so a lot of the lemon mixture ran down there. But it still was good!