Preheat the grill to medium heat. Grill salmon for about 5 minutes per side until it flakes easily. While cooking, mix half and half, flour, cheese, lemon juice, zest, garlic, dill, thyme, salt, and pepper.
In a skillet, melt butter, add the lemon sauce mixture, bring to a boil, then simmer for 3 minutes. Drizzle the sauce over the cooked salmon and serve immediately.