According to the on-line Radio Times it is Tuesday at 7.00pm as Bob has said. I missed it too i forgot that it was back after the World Cup had finished!
It was soo funny, I'll not spoil it for you, but they went caravaning, you can imagine the rest.
Do you have digital? If so, BBC has a 'Catch Up' section if you press the red button, that's how I watched it last night.