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Hi guys, which of these two foul drain run designs is better, 1 (red) or 2 (blue) and why?

I have received a quote for the design of the drains for my site. I am keen to do this early, well before my project starts, as I can ask for the works in the road done by my boathouse neighbour who is opening-up the road for their own purposes. They may well be willing to do this for me as in return I can give them access to my plot for site storage for the duration of their build. The timing would suit me as I need to go back to planning anyhow so wont be starting until after they finish anyway. I am told that they will be planning their work quite soon so I want to have my drain plan ready so I can hand it to them. At least that is my thinking. Am I going about this the right way? Note that I have already got a detailed survey of the local drains, including cover and invert levels, etc., which was prepared for the boathouse neighbour by this same SE company, and which the boathouse kindly shared with me. Having said that I have all the invert levels, the foul manhole nearest my plot was UTL ("unable to lift") so I do not have that invert level but I have it for the next manhole along upstream. I have been quoted by a local SE firm £1350 + VAT for preparing: (i) a foul drainage drawing showing external drain runs, manhole locations, and levels, etc. And (ii) a drawing showing the below ground surface water drainage for surface water to be discharged in to the adjacent stormwater drain via an attenuation tank. Given that this is the South East, I wonder if there is an SE-premium there? I wonder, does drainage have to be designed by a local firm or can I go to anyone nationally? By the way, must I have an attenuation tank for surface water? My PP does not mention anything about drainage.