Last Night's TV: Class act from a man of many parts

Summer Heights High, BBC3; Shopping Is My Life, BBC3

Some reviewers seemed to feel that Chris Lilley had been a little bit greedy in taking all three lead roles in Summer Heights High, a spoof documentary account of a term in an Australian high school, which is a bit like saying that Rory Bremner should stop hogging all the best characters in one of his shows. That's the point, surely: that one actor can turn his hand to an effete drama teacher, a surly Polynesian teenager and a head-flicking rich girl on an exchange from a private school. But even if the charge of artistic selfishness strikes you as a bit misplaced, it might alert you to one shared characteristic of all the people Lilley plays: their solipsistic insistence on always being the centre of attention.

This is a character trait that has always suited the mock documentary well, and long pre-dates The Office, the other obvious point of comparison for BBC3's bought-in comedy, which was a big hit when it originally screened in Australia. All the standard jokes of the genre are in place here: the way that self-editing is invariably ignored by the documentarian's cut, the fatal belief that the camera is a disciple rather than a prosecution witness, the sly cutaways to bystanders' reactions that nail an offence into place. But they're all in place in good shape.

The star of the show is undoubtedly Mr G, a monstrously self-regarding drama teacher who has taken advantage of the departmental head'scompassionate leave to promote himself to the post of director of performing arts. Mr G's proudest theatrical moment to date is the self-written musical Tsunamarama, which explored the tragic events of Boxing Day 2004 through the music of Bananarama. But last night's episode saw him seized by inspiration again, after an emergency staff meeting was called to announce that Annabel Dixon, a popular student, had been found dead after taking ecstasy. "She was what the kids would call a slut," Mr G explains, "which is a terrible thing to call someone who's just died, but there's no denying she was one." Annabel wasn't yet cold, but Mr G had already drafted the poster to pitch his musical response to the school's head: "One Girl, One Pill, One Hell of a Night."

Meanwhile, Ja'mie ("No offence, but I seriously hate fat people?") had decided to become the first year-11 pupil to have a serious relationship with a year-seven boy, a match that she pursued with a blithe indifference to his bemused lack of interest, from initial courtship to final, scalding split-up. "He's made me feel less hot...!", she wailed to the posse of "cool" girls she had co-opted, as she teetered back to their consoling embrace. And Jonah was in trouble again, getting a lecture from the school nurse on appropriate sexual behaviour after drawing a female teacher's attention to the semen stains on his tracksuit bottoms. Jonah is the school's foremost under-achiever – if that isn't a contradiction in terms – bringing to classroom disruption a focus and energy that would propel him to the top in any other field of activity. But he's also the one character who isn't a monster all the way through, the victim himself of a bullying father. It's a detail that gives a different kind of psychological texture to his scenes, and Summer Heights High would probably be a better drama if the same imaginative sympathy had been extended to Mr G and Ja'mie. Not quite as funny though, so thank goodness for Lilley's self-regard.

If ever a genre needed spoofing, the lifestyle therapy genus surely qualifies, in which television stages an intervention to save some hapless sap from their addiction to cheese string, or online bingo, or, in the case of Shopping Is My Life, to sprees of mouth-foaming consumerism. Astoundingly, they've managed to squeeze four hour-long programmes out of this concept, which is good going considering that 20 minutes would be stretching the raw material beyond its natural elasticity. Person shops too much, we gawp at their ludicrously over-stuffed wardrobe, listen in as they get a bit of McTherapy about the emotional voids they're trying to fill, then sign off with an upbeat claim about how their life has been utterly transformed.

Two "experts", in this case a stylist and a personal-development coach, set up bogus challenges for them to meet and the camera seems to have a suspicious ability to be on hand for every moment of crisis, despite the fact that the makeover process is supposed to take 10 days. In last night's episode, Nicola Chick, who sounds like she's a character from an abandoned Martin Amis novel, discovered that sweeping up pig shit and stumbling through a dance number at the local am-dram club is infinitely more fulfilling than buying another bottle of self-tanning cream to go with the eight that she's already got. Good luck to her, I say, but the only thing more boring than watching her arrive at this revelation would be shopping itself.