The best I can figure out is that the last British king to lead in battle was George II, at The Battle of Dettingen (1743), the last British prince to fight in battle was George VI at a turret officer at the Battle of Jutland (1916).
Prince Andrew, Duke of York, was in attendance during the Falklands war and was part of the rescue effort for a torpedoed ship, but was not allowed to participate in battle.
The last English king to lead his men in battle was Richard III.
The last English king to lead his men in battle was Richard III.