Pick of the day: Derry Girls

9.15pm, Channel 4

The Northern Ireland peace process is being negotiated at the start of the third and final series of Lisa McGee’s sitcom about four Irish Catholic schoolgirls (and one English boy) coming of age in Derry/Londonderry during the Troubles. More important for Erin, Orla, Clare, Michelle and James, however, is that they are waiting for their GCSE results and confidence is at rock bottom after headmistress Sister Michael (Siobhán McSweeney incorporating the crutches from her real-life accident) has intimated that they might have failed. There’s a subplot about the Quinn family cat, along with a big-name guest whose identity I am forbidden to divulge.

The Great Celebrity Bake Off For Stand Up To Cancer

8pm, Channel 4

Olympian Sir Mo Farah, Strictly Come Dancing judge Motsi Mabuse, actor Katherine Kelly and actor-comedian Ben Miller line up for the latest charity edition. They make meringue roulade and traditional Italian biscuits, before rendering a favourite childhood memory in the shape of a cake for the showstopper.

Freeze The Fear With Wim Hof

9pm, BBC One

Dutch extreme athlete Wim Hof has been proselytising the benefits of cold-water swimming for decades, and has accomplished such feats as running Arctic marathons barefoot and submerging himself in ice for two hours. Prepare for virtual frostbite as, in this new series, he challenges eight celebrity “victims” to undergo various freezing endeavours in sub-zero temperatures in northern Italy. Lee Mack and Holly Willoughby present.

DNA Journey

9pm, ITV

“What I know about my family could be written on the back of a Smartie”, says Maureen Lipman as she embarks on a genealogical quest alongside Rula Lenska. They met four years ago on the set of Coronation Street, but while Lenska has Polish counts and countesses in her illustrious family tree, Lipman says “I’ll basically be in Hull”. Wrong.

Compulsion

9pm, Channel 5

Leanne Best plays Jenny, a PTSD-suffering paramedic self-medicating with a gambling addiction. When new friend Sasha (Anna Chancellor) learns that Jenny is in hock to a loan shark, she offers Jenny a dodgy way of repaying the debt. This thriller plays out over four consecutive nights.

Julia

9pm, Sky Atlantic

British viewers are most likely to be familiar with Julia Child through Meryl Streep’s portrayal of the pioneering American TV chef in the 2009 movie Julia & Julia. This new HBO drama stars our own Sarah Lancashire as Child, whose 1960s show The French Chef introduced many Americans to Gallic cuisine. The angle here is Child’s battles with dismissively patriarchal TV execs, while there’s a healthy input of Frasier acting talent – her husband is played by David Hyde Pierce and her best friend by Bebe Neuwirth.

The Witchfinder

10pm, BBC Two

The Gibbons brothers’ comedy about 17th-century witchfinders has improved, but still hasn’t quite lived up to the promise of its cast. Matters conclude in Chelmsford, where Gideon and Thomasine (Tim Key and Daisy May Cooper) finally come face to face with the Witchfinder General, Matthew Hopkins – played with great relish by Reece Shearsmith.