question: What was the host for the semi final heat, when Terry Wogan was the National Final main host, and Gaby Roslin was the National Final co-host?
answer: SELECT semi_final_heat_host FROM table_name_24 WHERE national_final_main_host = "terry wogan" AND national_final_co_host = "gaby roslin"
context: CREATE TABLE table_name_24 (semi_final_heat_host VARCHAR, national_final_main_host VARCHAR, national_final_co_host VARCHAR)