I know a few LDS's up here offer the combined OW/drysuit option just because of the conditions up here. I don't want to be anywhere near them when they are doing their first OW checkout dives combined with drysuits...but....it is MUCH warmer to dive those waters in a drysuit. I did my OW checkout dives during an LDS trip to warm waters, came back, and did my drysuit course before I would even consider getting in the water here (mountain lakes of 4C/39F).
You should be prepared that you just might end up liking cold water diving after all, though, or that diving a handful times a year is not sufficient and you want to get in the water more, and you will definitely want a drysuit. I won't get into the water up here without one! I don't think the course is a MUST if you have a good mentor who can teach you the tricks of the trade and how to do it safely, but I did take the course anyway since it was a very low cost for me to do and I was able to try out a few different suits until I figured out what I wanted for myself to own. I would recommend the course. Some places will not rent a suit to you if you do not have the course, and I don't blame them after seeing a few people pop up to the surface.
I love warm water diving, but there is something also very unique and interesting about cold water diving. And cold water diving does not have to be 39 F, for me I consider basically anything below 70 F to be coldwater! Get the right drysuit, and not only might you be able to dive more often, you may even appreciate having it on the "warm" water vacations.