sorry but we are 17 th edition now and are you saying that a socket ring main should not be rcd protected!!!!
RING FINAL CIRCUIT!!!!!
you have no idea of electrical circuit design, no idea of the regs, and no idea on how to give sound advice.
Not all '17th boards' (what ever they may be) are dual RCD, you could install any configuration of board, it could be a main switch upfront with RCBO's and MCB's, it could be a split load board with MCB's and RCBO's on the main switch side, MCB's on the RCD side, it could be a dual RCD board with non protected ways that can incorporate RCBO's or MCB's, it could be a tripple RCD board ...it could be..it could be.... possibilities are endless.
Not all circuits with sockets require RCD protection, prove us ALL wrong with a regulation number to the contrary.
Did you used to be a kitchen fitter / have you been on a recent 5 day 'wonder boy' electrician course (where you possibly got 'part P-ed' too) ??
Wiggles, listen to the well thanked knowledgeable posters on here. You have some good ideas and seem to be thoughtfully constructing your installation