I swim upstream on this issue.
First, don't buy a horse at all. Get him to a good, classical instructor. English is best because it's the most challenging. He'll learn to feel the horse much more quickly in an English saddle if only because there's less of it than a Western saddle.
He should ride for the first year or two on a trotter. This will will teach him much better balance. It also enhances the ability to feel the horse move.
When you're sure this is for real and not a "passing fancy" then look for a horse for him.
Now a lot of guys, particularly from the Western world, figure English is "sissy." Would you call this "sissy?": Reganjumping.jpg Photo by Smile225 | Photobucket
Good look, too: Reganinbreeches.jpg Photo by Smile225 | Photobucket
(These are from my "Real Men Ride English" collection.
But, in all seriousness, lessons first then a horse. UNDER NO CIRCUMSTANCES ARE YOU TO TRY AND TEACH HIM TO RIDE!!!
Trust me on this; it won't go well for either of you.
Getting a spouse on board as a rider is a Very Good Thing but there are million ways for the effort to "go south." Find a good instructor and let them do the work. It will cost money; it can save a relationship.
Good luck your project.