I'd expect subsequent episodes to be better than the opening one, because that's how it works generally in English sit-coms, they try to introduce everything in the first, and it's overcrowded.

Trouble is that all the "lines" are just space fillers and not actually funny. True, lines shouldn't just be space fillers - but God preserve us from shows that try to have funny lines as such, "jokes". The humour needs to arise out of the situations and the interplay between characters, and that's what the lines are mean to do. And that is the context in which lines that wouldn't be that funny become funny.
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I see there are rumblings from the WI about Jam and Jerusalem:

WI group not amused by Jam and Jerusalem show

A new sitcom about a village guild of women who range from the comically deranged to the spectacularly stupid yesterday drew fire from the Avon Federation of Women's Institutes. Its secretary, Ros Knight, said Jennifer Saunders' BBC1 show Jam and Jerusalem, which features Dawn French, was in poor taste. "It plays to the worst side of people's nature and I don't like it at all. I'd like to see it taken off the air." The BBC stuck by the programme, saying it was intended as "an affectionate portrayal of the lives and relationships of the women that make up the group".

Actually I suspect that it's likely to do wonders to help the WI recruit new blood. Of course that might be what they are really worried about...