How much food did prisoners get during world war 2?

In England, very little. In 1940 you were allowed to spend 1s10d (one shilling and ten pence, twenty pennies, a twelfth of a pound) per person per week on meat. B7 1942 this was down to 1s - a twentieth of a pound. Early in the war, a shilling would buy thre or four pounds of lamb, but prices rose as time went on. It was impossible by 1945 to have meat every day without cheating. Please remember also that rationing did not end with the war; in the UK, meat came off the ration only in 1954.