Germany had plenty of sympathisers in Ireland. When pows were given parole to go to Dublin to study, and lot of people were eager to host them. If a German with connections had escaped, it wouldn't have been impossible to hide in the population. The ports were tightly controlled so access to ships was difficult but not impossible. It wasn't until later in the war and rationing began to bite that public sympathy for Germany faded.
You would need to be one deranged committed Nazi to want to escape especially later in the war.