I cannot go to the surface yet, I need to finish the first challenge. I do not have food, only 4 soldiers and no extra workers. On the surface icon there is a lock displayed and the exits are blocked. So, how do I get to the surface?
You don't need to unlock anything to go to the surface in the formicarium. Just click the lock - it is one of the tips that appears but many tips get missed. There's likely something we can do with text appearing at the bottom of the screen to remedy this.