Cleobeach,
If I read you correctly, you are land based on Virgin Gorda.
If you avoid the time between 9:30 and 3:30 you should be
able to avoid any crowds and show you're newbie friends
the kind of special experience you're looking for.

A suggestion assuming typically calm water conditions

Park at the Spring Bay National Park and walk about 200 yards
to the beach area (the Crawl)
Walk to the left (south) along Spring Bay to the end.
Put on your snorkel gear ( there isn't a foot path) and swim about
15-20 minutes to the Bath's entrance.
If memory serves me, there are two large boulders to go between
At any rate, you'll see the flag displaying wave conditions at the entrance
If you go in the am, you can have a snack on your return to the Crawl
but you'll need to pack your own as there are no facilities other than
a picnic bench or two and a bbq grill
If you go in the pm, a bottle of wine and sunset at the Crawl can be a
very nice way to end the day
The snorkeling between Spring Bay and the Baths is pretty nice,
certainly nicer than the walk down and up to the Bath's entrance at the top
Have fun

Mike