How do I bury pipes in concrete slab?

[RRRRRR]

Hi- I'm burying 15mm barrier mains water pipe, and CH barrier in a kitchen concrete slab before Jabfloor insulating it. (Basically I think it will be easier than chanelling out the underside of the Jabfloor for the pipes).

Is something like JG 15mm conduit OK for this? Or is 22mm easier/ better?

And can I/should I use foam pipe insulation in the concrete for the CH pipes instead of conduit?

Any help gratefully received. Thanks!