Bring patience, not because he's going to do anything wrong but you're going to be prevented from doing some of the stuff you ant to do while you look after him.
get him introduced to the people around you (as long as you're comfortable with that) so that they're happy to keep an eye out as well.
Teach him to ask for directions to the reception in case he gets lost
Have some stuff to entertain him if the weather is rubbish and you're not able to move about much
Make sure he's warm enough at night
Plenty of changes of clothes, there's no laundered in Bridgend (the nearest one is Pyle)
He's going to have a great time, I don't know where you live but there's so much freedom at the moot for the kids, they love it.