right, from memory:
nudity & sex: Rare, but heavily implied. There's lots of afterglow stuff, some heavy petting as Jay said. oh and they do that ever-so hollywood thing where nobody ever walks around in the buff after sex. Ever.
Lots of swearing. No way around that...but it's not ott. Just how people speak in pretty fraught situations.
Gore is a bit like the sex- each episode opens with a death, so sometimes it's innevitable and a bit gruesome but largely off screen and implied.
There's also a whole lot of dead bodies, as you might imagine. Most of them are naked, or fig leaved.
It's all rather good though, it'd be a shame if you felt you had to send it back.