I take it the book you're reading as no Biblical basis?
Originally Posted by chad
Acts 12.1-2: About that time Herod the king laid violent hands on some who belonged to the church. He killed James the brother of John with the sword.
This was when most of the Apostles had not yet left Jerusalem for missionary travel work.
Regarding Paul, most of the earliest Christian writers claim that he successfully went to Spain (as he had planned to: Romans 15.24,28), before returning to Rome where he was martyred. No one gives much room for him to have gone to Britain.