Split consumer unit replacing one RCD with an switch/isolator if necessary

Hi,

Can anyone recommend an 8 MCB split consumer unit I can install with four MCBs drawing current through one RCD - for new bathroom, kitchen sockets etc;

and the other four MCBs eventually drawing current through the second RCB - but where if necessary the second RCB can be replaced ith a two pole isolator?


This has to be done in two phases (due to cost and time) and I'm orried I fit the consumer unit for the four new circuits using one RCD, then find out some problem with the old wiring trips the second RCB leaving the second half unusable until it can all be replaced which might take some time as the second half of the installation is circa 1930s lighting about 5m up in the main room of an old chapel.


Or is my planned strategy flawed?

Jonathan