I just rewatched it in iplayer. Absolutely brilliant! I also really enjoyed Amanda's descant and remembered a thread on MN a while ago in which most people agreed that singing descant in carols and happy birthday was attention seeking and I have stopped myself ever since. The scene in the bedroom at the party is genius, it actually made me cry with laughter (which I rarely do).
I think Motherland is one of the very best comedies of recent years. It's not just funny but clever and poignant and the characters are so well developed.