To my knowledge it has not been decided which SAR flight he will go to but he would certainly be welcome at Chiv.
As to his capability for the job - having never flown a Sea King or any SAR training before he was able to complete drum winching in light winds and a live standard deck, all in 1 hour 30. I know this will invite comments about how easy SAR must therefore be but William is no idiot and can fly a helicopter perfectly well.
Whichever flight he goes to will see an upturn in its job tally as countless females put themselves in peril in the hope of being rescued by a Prince