He's a teacher who has the hots for one of his students. Also, he's incredibly inexperienced.
I suppose it is in some ways one of Pulp's more socially irresponsible songs, but it's a comical character sketch, not an endorsement of teachers persuing students. The goofy, catchiness of the song goes a long way.
Maybe I just come from trash, but when I was in High School I noticed plenty of male teachers ogling the female "student body", and there were plenty of students with the hots for their teachers. So I've always found PTA's political incorrectness quite refreshing.
It's a sign of the times that one isn't it? If that single were released today, I'm fairly sure that PTA would be the song that sparked tabloid outrage, whereas probably no one would bat an eyelid at Sorted.
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"Yes I saw her in the chip shop / so I said get yer top off"
