The actress will play food technology teacher Val in Roger and Val Have Just Got In alongside Alfred Molina as her on-screen husband.
"It’s so bold," French told What's On TV.
"I wanted to do another sitcom, but one quite unlike anything I’d done before. I thought it would be very interesting to do a two-hander and something set in real time.
"This seemed so different. It’s challenging, but we think it works!"
Teasing her character, French described Val as a "minx".
"She gets her pupils to do ironing practice on her curtains. Roger and Val don’t like authority," she said. "They live above the law. They have no other distractions. Inside the house, they can simply play and amuse each other with stories."
She added: "Their home is very busy and full of stuff – all their enthusiasms are fully realised in there. They never venture outside it. They’ve created a magical universe where all the diversion is centred on them."
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