Hi I am a aspiring cake decorator from the tropical isle of Jamaica and would like to know what is causing me not to have a smooth surface when I lay my fondant, Also who has a tried and true vanilla cake for this purpose. Thank you in advance for any help provided there is the picture below 

Are you using any type of icing or ganache under your fondant?

yes I do it is a butter-cream recipe i got from cake supplies plus using high ratio shortening 

With buttercream make sure you are not putting too much on. Just a thin coat works for me, then I let that crust a bit, I lay a smooth paper towel on the buttercream and smooth it with a spatula. You can use a smooth paper towel or wax paper. Then I lay my fondant.

I used to get bumps too and it was because I was using too thick of a layer of buttercream and I wasn't smoothing it well enough before laying the fondant.

I have used a variety of cakes and they don't seem to be the cause of lumps.

I do have my go to recipes posted on my blog, they all work wonderfully under fondant.

Hope this helps

Your cake design is beautiful!