Division of installation is a balancing act between cost and functionality. The
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced by equipment in normal operation.
is a real problem and it is down to a risk assessment.
You can draw 334 amp at maximum load on all circuits, but you will have only a 100 amp maximum main fuse and one has to consider is it really needed to split into so many circuits? Also you must decide on what is grouped on to one RCD.
Oven, rings, garage, immersion, shower and hot tub can all easy cause a RCD to trip where as the risks with lights, smoke and boiler are much lower. The idea is
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit.
and that can be done in many ways. Having ring final and lights for each area on a different RCD so with the use of standard lamps any RCD failure will not plunge one into darkness is a common approach. However having so many items which could allow a build up of protective conductor currents the risks in your case is still high.
Using RCBO’s will remove the problem but also will increase cost so a balance is required. So first thing which hits one is immersion and boiler in the loft having a single feed and three FCU’s would seem to at least remove one MCB/RCBO.
Ovens 3 x 32A and three rings is the next which stares one in the face could you use a kitchen consumer unit?
I always question separate supply to items like alarms having some thing else off the same supply means if for example it tripped while on holiday on return you would find something not working if shared but on a dedicated supply you may never notice.
All my lights come from the same RCD however my stairs have a battery backed light so a failure of a lighting circuit does not produce a danger.
Not all RCD’s are equal and I am told the X-Pole is very good at not tripping, but if I was doing my house again I would want more than 2. In the main this means either more than one consumer unit or use of RCBO’s. The latter will not fit all consumer units and so selecting two or one consumer unit would depend on if I could fit RCBO’s.
Every fuse or MCB creates heat. So consumer units should be in free air not in a cupboard of oven housing. Same applies to sockets and 13A plugs. The plug should be in free air, but there are exceptions where clearly it is not going to be a problem.
In Wales I can see why a kitchen fitter would be a scheme member, but where only doing minor works in England why pay out all that money. You don’t need to register minor works in England except for bathroom work.
As I said down to cost, but likely cheaper to have two consumer units each with two RCD’s than having all RCBO’s so likely I would use two consumer units.
As to what you can notify through the scheme provider there is only one way to find out, and that is ask your scheme provider. With bathroom, new circuit and consumer units being all that anyone in England has to notify having a scheme which excludes some of that would seem rather pointless.
