If you are a parent and have not watched any Doctor Who, I would recommend watching this one with your kids. Not only is it the first to be sexually suggestive, it is also the best story to this point. So if you ever hope to enjoy the show, this is a good chance.
This episode marks the first appearance of Captain Jack Harkness, who is a very sleazy character. Jack is an old-fashioned adventurer, like Robin Hood or Captain Kirk. He is also sex-starved and so he flirts and makes suggestive comments to everyone he meets. And I mean everyone.
The dialogue between Rose and Jack is mostly suggestive. Little kids might not get it. Big kids probably will.
Captain Jack squeezes the butt of a male soldier, flirting (the actual contact is off-screen).
There is some scary stuff. There are little children with gas masks and they are provide a quite unsettling mood.
A doctor turns morphs into an alien and a gas mask extends from out of his mouth.
What made the alien boy finally stop? (He acknowledged who his true parent was.)
How is that reflected in people becoming Christians?
Once the glowing yellow stuff was able to see what the true image of a human was, it was able to heal people. Compare that to the way Jesus was able to restore the true image of humanity.