Personally, I would rather be certified prior to arriving. I really wouldn't want to devote my vacation time to learning how to dive upon arrival. The more you can get accomplished prior to arrival leaves you with more time to have fun and explore.

Most resorts offer what's called a Resort Course and will permit you to dive during your stay at their resort only.

As far as which resort... it all depends on what you are looking for in a resort. JE is north of the cut and requires you to take a water taxi or their boat back and forth to go into town. Victoria House is south of the cut which makes it easier to come and go into town, etc without having to worry about getting a boat. Both have appealing aspects...