Excellent, thanks for the advice! I think I'll go for a vanilla sponge as most of the children will like it. I'll need to have a look at those recipes GoldenGreen. I think my SIL has used the madeira one in the past and thought it was good.
Buttercream and jam should work well for the filling too. Haven't used yogurt before wanna, so will certainly look into that, thanks for the tip.
Now all I need to do is work out how to do the Octonauts. I've found a tutorial, but they never turn out the same do they!
What's the best choice of cake for a children's birthday party? It's going to be a 2 tier round cake and I was thinking perhaps a madeira cake for strength? The other options would be a vanilla sponge or chocolate cake, but DS isn't so keen on chocolate. It will be covered by sugar paste and my very best likeness of Captain Barnacles et al.
Also, what kind of filling? I usually go for a vanilla buttercream, but would some jam go down well in addition to that?