Preheat the oven to 400 degrees F. Put the tomatoes, sugar, thyme sprigs, 1 cup water, 1/2 teaspoon salt, and pepper to taste in a small saucepan. Bring to a boil over high heat, then reduce the heat and simmer, stirring occasionally, until thick, about 30 minutes. Meanwhile, mix half of the lemon juice, the chopped thyme, mustard and Worcestershire sauce in a large bowl. Season the flour with salt and pepper in another bowl. Heat a large cast-iron skillet over medium-high heat. Season the drumsticks with salt and pepper. Dip in the mustard mixture, then dredge in the seasoned flour. Melt the butter in the skillet and fry the drumsticks, turning, until golden on all sides, about 6 minutes. Transfer the skillet to the oven; bake until the chicken is golden and a thermometer inserted into the center registers 155 degrees F, about 15 minutes. Add the remaining lemon juice to the tomato jam and season with salt and pepper. Serve the drumsticks with the jam and biscuits.