In the fourth series, Susan is looking forward to the birth of her first grandchild, but dreading being a grandmother. Nick is getting fed up with living in his ghastly flat and trying to think of a way to move back into the family home. The gap between Michael's IQ and the rest of the family's seems to be increasing, but so is his libido. And Abi is still Abi, only more so! As for perennially put-upon Ben, what with a new arrival causing chaos in the surgery, being forced to take tango lessons and being officially declared dead, life is just one long major-league cirsis.…