Small kids and crafts, you either have to let them join in or protect your space. Maybe make them their own desk area and stock it with things you no longer want/need to use.
My motherly advice is that you may have to learn to be creative no matter what is going on around you or you may never be creative again. You will work it out. Try not to be overwhelmed. The important thing is being a mother - congratulations! The rest is just extras.