Looking for the name of a particular UK sitcom & actress

Hi All
I need your help here; I was doing a Sitcom writing course a few years ago and I'm looking for the name of an Uk comedy actress that was in a clip I saw from a Sitcom I don't know the name of. The only way to find it if describe the scene in the sitcom. The sitcom I'm sure is relatively recent sitcom, not sure how old.

A Mother (the actress I'm looking for) walks into a primary school with either one or two infants ( I cant remember how many), the school is empty, the parent only then realises its half term but she didn't know, a teacher confronts her and the parent tries to hide the fact that she didn't know it's half term. She makes up a story that she has come into the school to report her children are being bullied. She spots a school bag hanging on a hook the only item there with a child's name on it and she says ...........name of child is bullying my child.

Thats all i can remember.

Anna Maxwell Martin - Motherland

Thats her. Thank you so much Bonzo much appreciated :D

Who ran the course?

Organised by Alfie Noakes with Stephen Carlin over in Hackney East London

I only want to add that there are also:
"Mum" sitcom (Lesley Manville) - UK - excellent one.
"Mom" sitcom (Allison Janney) - US - created by Chuck Lorre but vvve-e-e-rrry boring.