I've made one Fondant figure - a Super Mario and I forgot to add Tylose to my fondant.
Will I have trouble with it sagging do you think? Will I have to re-do it again?
OR will I be ok?
Oh boy, this is a tuff one to answer. It really does depend on the weather where you are, how stiff you make your fondant and how important this figurine is. I haven't had any luck at all with figures in plain fondant - unless you used a purchased kind like Duff's fondant which is half fondant and half candy clay. It sets up very securely in colder weather like we're having in New England right now. Will the fondant figure be in a warm room, is it a tall or squat figure - squat would be best. If it's tall I would do it over again with all gumpaste or 50/50 GP and Fondant then secure to the cake with a skewer . So sorry I can't help you more but if it's for a paying customer and it's tall and this is really important, yes, do it over - if only for your peace of mind.
Are you letting it dry before using it? It will probably be okay but it does depend on how soft it is, and how long you have to let it dry before using it.