I lived 700 miles from family when I was expecting my second baby. It never crossed my mind not to visit them in the later months of pregnancy!
Roads are so much better now than in the 1970's, almost all dual carriageway, lots of service stations available 24 hours, inexpensive hotels if you want to break the journey up, though I did a shared 14 hour drive yesterday (admittedly not while pregnant but I'm no longer a spring chicken!) and feel fine today.
I think it will be a nice break for your Dd.
Washing bio gel or quid in the drum