I just watched "Men Against Fire." There is some gore in that one, a man is stabbed in the chest repeatedly and blood is shown. A woman is also shot in the head and you see the bloody wound afterwards. Nothing too gross - no muscles or bones or anything - just bloody.
There is nudity in this episode. In a dream sequence, a woman is shown topless for about 4-5 minutes. There is an orgy-like sex scene. Lots of boobs, thrusting motions, moans, implied touching. Nothing below the belt shown.

The episodes are more disturbing, no real nudity to speak of and not any gore. This is TV that makes you think long after you watch it. I agree, you may not want to watch 1.1, if you're concerned about you're parents seeing you watching weird subject matter.

Don't watch the very first episode if you're afraid of your parents seeing something weird. There's no nudity, but a guy performs a gross sex act and it's obvious what he's doing. The act is appalling and turned my spouse off to the show forever. He won't bother watching anymore episodes, which is kind of sad.
The only gore I recall is in "Playtest." If you can handle the guy's face melting in Indiana Jones, you can handle the scene in Playtest.

Or Channel 4 (they're known for being more radical than the BBC).

It's very much like twilight zone and outer limits if done by the BBC. Also only one episode (season 3 dream sequence) has nudity and it was very brief.

I think it's the ideas in some of the episodes that people find most disturbing? which is partly why it's so clever.

No worries on either score, as best I can remember. There are violent situations and sexual situations, but nothing "in your face." It's a tasteful show.
"I know this ain't gonna sound good, but I just shot two people."

I'd say it has neither.