Emily's pal said her actress mum Kate Robbins “can’t wait to be a grandma”.
Kate, 65 — who recently appeared in the Channel 4 drama The Couple Next Door — is related to Sir Paul McCartney.
Emily’s father, Keith, is a musician, who used to be in the 1970s pop band Child.
Emily's friend said: “Her relationship with Alistair has gone from strength to strength and they’ve moved into together.
“Family is everything to her — she comes from a big one herself and is really close to all her siblings — so she can’t wait to start one of her own.
“They’ve all rallied around her and delighted in the joyous occasion."
Emily and her boyfriend Dr Alistair Garner recently set up home together to prepare for their baby’s arrival.
A pal said: “Emily is delighted by the happy news and has been pleased to tell family and close friends about her little one on the way.
“It’s the perfect end to her year and she feels over the moon.
"Emily is more than ready to be a mum and it is something she has dreamed of her whole life."