Complex sentence: They reached the finals at the ATV studio in Wembley despite a roster of 600 entries, and went on to win-then being invited to sing on Bert Weedon's TV programme Lucky Dip that same day.
Split into simpler sentences: They reached the finals at the ATV Studios in Wembley despite a roster of 600 entries, and went on to win. They were then invited to sing on Bert Weedon's television programme, "Lucky Dip" that same day.