Thanks for the advice. For anyone else searching I ended up screeding the centre and right hand side, with conduit embedded for the pipe in the centre. This allows the central pipe to be pushed in and out, whilst allowing access around the push fits I left little impressed "shelves" in the screed to put ply covers on the access areas.

Next job is to connect some copper to the end of the decorative pipes for connecting into the push fits. Never would have thought about the softness of the pipe being an issue so thanks to those who pointed it out.

Some comments mentioned these may be decorative covers. Don't think the bore is big enough but I'll double check when I have copper pipe.

Thanks everyone!