Ok so here is the final design
4 floors, 5 manifolds. 1 floor has a 12 and 10 port manifold, and the others either a 10 or 12 port manifold. All pipes to have 150mm centres. Going for smart stats that apparently have a couple of years life in them. Maybe I should have gone with the hard wired stats like I did in the current house but anyhow, decided the smart with app control.
We will have 2 boilers linked for the entire house