Preheat the oven to 350F. Spray a 8.5 x 4.5 or 9 x 5 pan with baking spray. Or, butter the pan, sprinkle with flour, and tap out the excess flour over the sink.
Combine the blueberries and 1 tablespoon of flour together in a small bowl. Toss to coat the blueberries with flour.
In a medium bowl, whisk together the 1 2/3 cups of flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, sugar, lemon zest and thyme on medium-high speed until light and fluffy, about 3-5 minutes.
Add the vanilla. Add the eggs one at a time, scraping the bowl after each one has been added.
With the mixer on low speed, add the flour mixture to the batter in the three additions, alternating with the milk in two additions, beginning and ending with the flour. Mix until just combined.
Remove the bowl from the mixer and fold in the blueberries.
Pour the batter into the pan and bake 45-55 minutes or until a toothpick stuck in the loaf comes out with few dry crumbs.
Cool the loaf in the pan for 15 minutes on a cooling rack. Remove the loaf from the pan and place on the cooling rack to continue cooling.
In a small bowl, whisk together the confectioner's sugar, lemon juice and heavy cream until thickened and well combined.
Pour or drizzle the glazes over the warm (not hot) loaf cake. Top with extra blueberries and garnish with fresh thyme. Cool completely before slicing and serving.