As a L plate BIABer myself (4 brews), I'd suggest going with a simple recipe of a beer your familiar with. In my kit days I came up with a Aussie Pale Ale recipe using Coopers Aussie Pale, Galaxy, Carapils and Coopers yeast which I was really happy with. When I moved to extract, the first brew I did was an extract version of this recipe so I could gauge the difference. Subsequently, my first BIAB was an AG version of the same recipe for the same reasons. Second brew was same recipe again, slightly tweaked. Third brew was a Citra/Amarillo Pale Ale based on a beer I'd tried at a small Sydney brew pub one night when I was lucky enough to have a chat to the brewer and get a rough idea of the recipe. For my fourth, I've done a Marris Otter / Centennial SMaSH to about 33 IBU. No idea how this will turn out but I did this one as I've never used Marris Otter or Centennial and hope it will give me a feel for the two.
So basically, I'd recommend a beer your familiar with so you've got a reference point, and a relatively simple grain bill / hop schedule. If your expereince is similar to mine, you'll spend the first few brews getting to know your system as far as efficiency and volumes go. I was all over the shop on the first three brews, but got closer to hitting my numbers on the SMaSH brew so I'm getting to know my system...slowly.