New build - Drainage Design

[dbyter]

We have planning permission for a new build and this shows the drainage design for the house. We've unearthed the pre-existing sewer connection (red dotted line) which served the demolished house and it is located in the area circled red. Thinking that the current design looks pretty sensible and we can change direction and follow the red line, putting in a long radius bend towards an i.c at the circled point roughly in that circle area where we connect to the existing pipework? 

I'm asking incase anyone with knowledge thinks that changing the route and instead running it under the slab more directly is any sense. From reading comments in other posts it seems the general consensus is to run drainage outside of the foundation wherever possible?

The waste pipe running the depth of the building shown at the wall of the bedroom is there because of an upstairs bathroom above the plant room next to the bedroom, architect didnt think it could work running through 1st floor joists given warm roof with exposed joists on the lean to section. He said a long swept bend coming down through plant room and into slab with rodding eve at front of property might work well for this? He has suggested the SVPs in roof vent tiles. 

Given there is that pipe running the depth of the building, and no obvious way round that I guess I'm wondering if the whole lot could just come from back to front under the slab and then across the garden from roughly that rodding eye outside the bedroom location. 

Thanks for entertaining queries from an enthusiastic DIYer, in way above his head!