The guys above said it pretty well. 5 weeks for bulking isn't much, but it's not impossible for you to put on several pounds if you're training and eating right and depending on your current physique and training experience.
Creatine can help your training, but any weight you put on directly from the creatine will likely be water retention. Go ahead w/the creatine, train hard, eat a lot of quality food and it's possible for you to put on some size before this wedding. It may not be highly noticeable in your suit, and you'll probably be pretty smooth.
Are you already lean and just wanting more mass, or do you need to cut down as well? Knowing that 5 weeks for bulking isn't time to do a lot, you might be better off still training hard but cutting down if you're not currently lean. Look into an ECA/Y stack. Just all depends on what you need to do and the look you're going for.