It's fair to say that Catherine Tate has had an interesting couple of years; from her role in the American version of The Office to acting on the stage, I feel she's come a long way since her sketch show. However this week saw her revive one of her most popular sketch show characters, Joannie Taylor, for a one-off special Nan.

At first I thought Nan would be simply an extended version of the sketch show, but the plot of the programme was fairly endearing. It saw Nan being paired with teenage volunteer Alice (Ami Metcalf) while her grandson (Mathew Horne) is off building a school in Africa. The main thrust of the episode concerns Nan's taps and her constant fights with the council to get it fixed. In her own unique style Nan's interactions with council representative Miss Donnelly (Nikki Wardley) land her in hot water and eventually see her serve two community service orders. Eventually though Nan is able to save the day by allowing her Indian neighbours to host a wedding in her flat.

Anybody who loved Nan's foul language and bad attitude wouldn't have been disappointed by what they saw here. However I was surprised that Tate fleshed out the character especially in constructing a relationship between Nan and Alice. I feel the episode really benefited from the appearance of Ami Metcalf, who so good as the young Kathy Burke in Walking and Talking. Metcalf and Tate made a fine double act and I particularly enjoyed Alice's confrontation with Miss Donnelly. The focus on the bureaucracy at the council was also a story that most people could identify with and they could understand Nan's frustration and the way she dealt with the problem was completely believable.

Ultimately I found Nan to be funny, endearing and a sitcom that was well-paced throughout. If all the episodes are of the same quality as this special then I wouldn't mind seeing Nan return for a full series at some point. But for now I can definitely say that Nan was a big surprise as I didn't see myself enjoying it at all.

There's a lot that's very, very good about The Mimic, which stars the gifted impressionist Terry Mynott as lowly maintenance man Martin Hurdle.

It's the second episode tonight, but if you missed the first all you need to know is that Martin escapes his humdrum life by doing other people's voices - everyone from Alan Carr to Christopher Walken - and last week he discovered he has an 18-year-old son called Steven. Probably. We're still waiting for the results of the DNA test.

As a means of doing something more interesting with impressions than just going down the Dead Ringers route (or Very Important People, which was Mynott's last gig) this gets full marks for originality.

And the excellent supporting cast includes Ami Metcalf (last seen playing the young Kathy Burke in Walking And Talking) who plays colleague Chelsea, and Neil Maskell (fresh from playing Utopia's hit man) as a depressed newsagent whose foray into internet dating tonight is inspired.

But the mixture of occasionally crude humour and misty-eyed pathos is a tough one to pull off successfully. And that soundtrack is one dollop of syrup too far.

An offering from Sky Atlantic which is tempting Sky1 viewers is this new sitcom starring and co-written by Kathy Burke.

Set in 1979, Walking and Talking is an autobiographic sitcom in which Kath, played by Ami Metcalf, walks from school with her best friend Mary (Aimee-Ffion Edwards) and talk about their worries and everyday goings on.

Personally speaking, I found the actual walking and talking to be the least appealing bit. In fact I found it mostly dull and uninteresting, but maybe that's because I wasn't around in 1979 to experience what 'life was like back then.'

However things started to get interesting when the senior performers come to the forefront. These segments include conversations between two nuns that work at the school, played by Burke herself and Sean Gallagher in drag, and the worrying encounters the two girls have with local nutter Jimmy the Jew (Jerry Sadowitz).

It was a strange role for Sadowitz, but he was absolutely amazing. You don't tend to see him act that often, which he clearly can do by what I've seen. But the profanities were absent here too, which is certainly odd to those who've seen his stand-up. But despite this, he is still as intimidating and menacing. He plays the character perfectly.

Walking and Talking isn't perfect, but it certainly has its moments. No doubt it can be tightened up in various ways to iron out some of the minor issues...

Kathy Burke the writer, source and inspiration for Walking and Talking, corsets herself selflessly into a small yet lovely cameo as, basically, "angry smoking fecking Irish nun", who manages, while discussing Top of the Pops in a concrete Islington playground in 1979, overseeing children she hates, to reduce a fellow nun to hot salt tears over, of all things, the Teutonic origins of Boney M. Wonderful.

Mainly, however, Burke lets the phenomenal young Ami Metcalf recreate Burke's own adolescence with (from both talents) honesty and pluck and wit, verisimilitude and yearning. It's shot in a lovely leached-bone white, which wasn't all of 1979 but well, OK, most of it. Young Kathy (likes Keith Waterhouse, Play for Today, Porridge; hates wasps, Thatcher, dad when drunk, nuns) and her friend Helen debate fatness, chat-up lines and down-there stuff in a way which would now have them cautioned or sectioned or weeping on morning TV, and is as wizardly refreshing as the wind blowing through your armpit hair on holiday. The most uplifting thing yet this year, and young Kathy hasn't even got her trainer bra.

It's the 70s, so everything is a bit brown and Life on Mars. Busby-haired "Kaff", who is 14 and lippy, pogos around her bedroom to X-Ray Spex. This is the young Kathy Burke, as remembered by the actress for a new four-part series.

The sitcom follows the tomboyish teen (a superb Ami Metcalf) and best mate Mary as they amble around the streets of Islington. Co-starring Burke as Angry Nun and Jerry Sadowitz as Jerry the Jew, it's a total delight, with realistic rhythms of girl talk, and a smile of a soundtrack.

Having made its debut in Sky1's Little Crackers series of short films from 2010, Kathy Burke's slight but charming autobiographical musings return for a four-part series, with the adolescent Kath and best pal Mary as played by Ami Metcalf and Aimee-Ffion Edwards. It's virtually a two-hander, barring an exchange from her two bewimpled teachers and a puzzling cameo from Jerry Sadowitz, so a huge amount rests on the dialogue and performances. Burke's script invokes the comedy of recognition easily enough, as the awkward teens rail against the frequently baffling yet strangely enticing adult world of French toast, pubs and romance. But the genuine warmth of their relationship owes a huge amount to the young actors: Metcalf and Edwards are both wonderful, and reason enough alone to tune in.