Drainage for extension

[Mak80]

Hey all,
First poster here and looking for some advice on drainage for a side and rear extension I have in the pipeline. Architect has drawn up the plans to building regs but told me to sort out the drainage. I've had a read of past threads and understand straight lines to access points are important for WC's so I've taken a stab at how it could work although not sure the best way to pipe the middle bathroom wc. Is anyone able to suggest a good way of doing this? There will be a 'hidden wall' where the pipework will go behind for the wc and sink. Maybe what I've done so far could be done better too so totally open to everyone's expert opinions!
Attached an image of the layout I drew up ... pretty much all happens down the left side. I do have the surface water to deal with too but one step at a time I guess. Property is a detached bungalow with combined private sewers. Underlying soil is London clay.
Thanks in advance

 

[stevie888]

A bit like the surgeon asking you to sew yourself up!!

Tell the lazy git to do his job: he'll probably have to put a few grey cells in gear which I suspect is why he'd rather not do it.

You need to show existing pipes and chambers clearly as well as your suggested new work.

Your detail in the laundry is dire: stick a stubstack in the corner and a straight 100 pipe to the chamber

 

[Mak80]

Haha, I know right. As you can probably tell, this is all new to me. He was only too happy to recommend civil engineers who want a pretty 4-figure sum though ... I mean if I have to, to get something submitted to BC to get on with it, I have to, but then when I likely get a drainage installer company in to do this, they may end up doing things differently anyway!

I've attached an image of existing pipework that includes all existing drainage overlaid on the proposed extension.

Stub stack. Is that for the inside corner of the room or to be located at the corner of the exterior of the laundry room?

Appreciate the help!