You are on the correct path if perhaps not going in quite the right direction.
An RCD is looked upon as a miracle aid for the electrical industry where it is just an aid to correct design. Through out the BS 7671-2008 section and Regulations advise the electrician on RCd protection such as additional protection in the home 30mA and fire safey not exceeding 300mA so it is just the testing that is complicated.
MCBs are a little more complicated as they supply both overload and Fault protection. To design a system that incorporate just MCB protection alone you have to calculate Volt Drop, Rating Factors, length of runs and cable impedance, etc etc and this is something that can only be taught.
This is why we are taking your posts with that proverbial "pinch of salt", as it is impossible to have a generic book that will cover this subject