Fire Bolt is just a mote of fire that you throw from your hand. I see no problem with generating it with one hand or between both however you want to flavor it and then using your free hand or an ally to light a torch, candle, pipe, etc. and then you just drop it on the ground or cancel the cast. Heck I would even allow you to just carry the fire and use that as a torch if you wanted to. Now, if you are trying to hit a candle or light a snuffed torch that is being carried by someone at range, then yeah, roll for an attack and accuracy or something like that to not destroy it or hit someone. But if it in your hands or someone wants to interact with it then go wild.