Heat large skillet. Melt 2-3 Tbsp. butter and olive oil and cook chicken until no longer pink. Chop peppers, lettuce, tomatoes, and onion; keep separate. Remove chicken and place on cutting board to cool.
In same skillet melt 3-4 Tbsp butter. Sautee peppers, onions, and fajita seasonings. Add Worcestershire sauce. Cut chicken into cubes and add to peppers and onions.
Place salsa, cheese, lettuce, tomatoes, and chicken-pepper mixture on tortillas and roll up. Serve with chips and salsa.