Place milk, heavy cream, potatoes, and one teaspoon of salt in a saucepan and bring to a boil over medium heat, stirring frequently. Reduce heat and simmer.
In a large heavy-gauge soup pot, melt butter over medium heat, then add bacon and cook until crispy. Add garlic and cook until blonde. Toss in thyme and bay leaves and cook, stirring, for another minute. Add onions, leeks, and celery, and turn up heat, stirring and cooking for about five minutes. When vegetables are tender, reduce heat to medium and add flour, stirring until incorporated. Add clam juice and bring to a boil, stirring constantly. Pour in half of the cream-milk mixture, leaving enough cream with the potatoes to continue cooking them.
When potatoes are tender, add mixture to the vegetables. Bring the chowder to a boil, stirring constantly, then reduce heat to low, cover, and simmer for 25 minutes, stirring occasionally. Stir in clams. Add Tabasco, Worcestershire, salt, and pepper to taste.