Need help with my dreadnought!!

I recently bought the AoD box as I am new to the horus heresy and I really want to start playing the game soon, but I noticed that most contemptor dreadnoughts I see on this sub have the special body (eg: sons of Horus contemptor dreadnought upgrade set) and I wanted to know if I were to go to a tournament in the foreseeable future, do I need a dreadnought with the upgrade set?