If Bismarck defected, Britain would use it cautiously

What if anti-Nazi sailors brought Bismarck to Britain?

Britain would likely save and use the ship, but only with a large trusted contingent and perhaps away from especially sensitive theatres.

The ship would probably be retained as a useful asset. The Royal Navy would nevertheless distrust a complete German crew aboard a powerful battleship in sensitive home waters. British personnel, Royal Marines, Polish sailors, and anti-Nazi German exiles could provide supervision and the language skills needed to operate unfamiliar machinery. A distant deployment such as the Far East would further reduce the risk while allowing the ship to contribute to the war. A surviving captured Bismarck might later be transferred to the Soviet Union.