This is what I would suggest.
Hop on board the Disney-MGM Studios bus. Let the driver know you need to get to the Beach Club. This way, if he or she is able to, they MIGHT be able to take you directly, after dropping off other folks at the Studios. Not a guarantee... but it's sometimes a possibility.
If they are unable to, just exit at the Studios, and hop on board a Friendship Cruiser to the Beach Club.
For timing, I'd be out at your CBR bus stop one hour prior to your PS. It won't take an hour, but it's always best to plan for Murphy's Law.