Pity you weren't on the IOM a few days earlier for the Tynwald Day celebrations!
So you're on the IOM from Saturday to Saturday well, to my knowledge there aren't any organised folk clubs on the island. Eveything tends to be on an informal basis - sessions, in fact. Bearing that in mind there are the following :-
Saturday - The White House Pub in Peel - instrumental music emphasis with occasional songs - mainly Manx/ Celtic.
Tuesday - The Trafalgar Hotel, South Quay, Douglas - mainly Irish instrumental with the occasional song.
Wednesday and/or Thursday - Clinch's Celtic Tavern, North Quay, Douglas - instrumental with occasional song.
Thursday - The White House Pub, Peel - singing session.
Friday - Tynwald Inn, St Johns - as above.
Friday - Mitre Hotel, Ramsey - mainly Irish instrumental with occasional songs.
Good Luck