How do I reduce the acidity of homemade honey lemon juice?
You can neutralize the acidity of your drink by adding a half teaspoon of baking soda, but don't do this. Apart from fizzing up like a volcano, your lemon drink, or what is left of it, will taste pretty awful.

What you want to do is reduce the perceived acidity. This can be done simply by adding more honey. I suggest adding a teaspoon at a time until it tastes about right. I like about double the amount of honey you specified if we're talking teaspoons.