2 SIMPLE STEPS :First, you go on Creative. Now I know it's called Creeper SURVIVAL but bedrock is unbreakable, Right? you'll see what I mean in a second.You can use a seed, or just random, Then you build a base or a house out of Bedrock. I would put a Crafting Table , A Bed, A furnace ,A stone cutter and four large chests depending how many items your going to have. Second you of course change it to survival! Have fun! Follow if this was helpful!