There are no rules in triathlon that say you have to swim using the "xxxx" stroke. I have seen people walk the shallow end and dog paddle the deep end of the pool. I'm not kidding and they do it pretty fast. All you have to do is get from point A to point B in the pool and you won't have any problem with that. This sounds like a perfect forum for your first tri. Go for it and have a good time. Oh, and by the way, happy birthday!!!!