CREATE TABLE table_13917 ("Year ( s ) " TEXT, "Selection show" TEXT, "Venue" TEXT, "National final main host" TEXT, "National final co host" TEXT, "Semi final/heat host" TEXT)

What is the name of the national final main host at BBC Television Centre, and the selection show was Eurovision: Your Country Needs You?
SELECT "National final main host" FROM table_13917 WHERE "Venue" = 'bbc television centre' AND "Selection show" = 'eurovision: your country needs you'
SELECT "National final main host" FROM "table_13917" WHERE "Selection show" = 'eurovision: your country needs you' AND "Venue" = 'bbc television centre'