Combined attack

Is there anywhere I can view the combined attack rating of my fleet, I want to know how many super dreadnaughts I need to destroy a colony planet

With the current system take the population of the planet say like 450 million. Take the 450 x 18. This will give you a rough defense. Take that and divide by your ships attack power. Will tell you how many ships you need roughly. Shoot high for orbitals and any ships at the planet.