The English prisoners of the Germans are having a much different POW (prisoner of war) experience than Billy is. They have commandeered plentiful supplies through a paper error. Due to the wealth of food, clothes, and other supplies, the British do not suffer from malnutrition or cold. In fact, they are able to throw elaborate dinners like the one they had to welcome the American prisioners. They even are able to put on a performance of musical theatre.
The English experience stands in great contrast to Billy's and his fellow soldiers. After an uneventful capture, they are marched through the snow at gunpoint without proper footwear.
Vonnegut may be, with this episode, pointing out the absurdity of war (and life). He includes moments of great horror (like the firebombing of Dresden) along side the mundane and the transcendent.