Heavily pregnant woman who by her own admission isn't feeling well travels via ferry for hours and hours - I don't think so.
Also there is NO way at all she wouldn't have been spotted and tweeted/fb'd about. There's no hiding places on those ferries!
Hardly the Woolwich ferry, there are restaurants, shops, cinema, heated swimming pool, children’s entertainment and luxury cabins. Takes the same amount of time as driving through France to Spain.