Remove lobster meat from shell; coarsely chop and set aside.
In a large saucepan, melt butter over medium heat. Add onion, celery, and garlic; cook for 5 minutes, stirring occasionally. Stir in flour, and cook for 2 minutes. Stir in chicken broth; cook for 10 minutes, stirring occasionally, until thickened.
Add lobster meat and shrimp. Stir in half-and-half and Creole seasoning; cook for 10 minutes, or until heated through, stirring occasionally. Serve immediately.