Usually if they peak it means the oven is too hot/cooking to fast. Try turning the temp down 10degrees and cooking for slightly longer.
If it still happens - chop the top off so it's level. I tend to chop the tops as best I can (not very good... I'm cack-handed!) and then put them together with one cake upside down - because the bottom is usually really flat and you can fiddle with the filling to even up any problems if the two chopped ends are facing together. If that makes any sense at all!
That's fab RedRose! Is that your first model too?! I want to do a Waybuloo cake for LOs birthday, but the thought of making those figures fills me with dread!
ETA- Cocoa, I was just thinking RE waybaloo, it would be quite hard cos their heads are so big compared to their bodies, they might not stand up. You could maybe do them lying down in yogo poses? I think that would be easier too as their weight would be mostly on the cake instead of upright.