Glad you got good advice. We were building through COVID lockdown and it’s after effects. Many times I wanted someone to talk details on site or in a workshop but couldn’t.
I used TK, everything done off their design tool with at least 5 revisions. Phoned them a few times, not visited but they might be open for a chat in their office. Who is fitting it for you, probably more important to check the measurements on site.
I’ve got less than 200mm cover albeit close to the house. I would be concerned by a concrete mixer, cars exert relatively low ground pressure, and that is distributed significantly even 200mm depth. Also more confident about PVC pipe which will flex, than a rigid pipe.
Just show that on a drawing. I don’t know any specific requirements, maybe they vary between each LA. As long as they are not blocking any access or parking provisions, double they are interested in what they look like considering they keep giving us more of them.
No personal experience of them but found their website https://hbdsystems.co.uk/hyline-sliding-doors/
Would be surprised if they manufacture themselves, maybe rebranding something from Eastern Europe?
Doesn’t look right to me, I would expect to see at least 1m above the gutter level.
This is what AI says https://share.google/aimode/7iJ9jUTYOfNaOr9Mf
so, no it isn’t correct. Should have a HETAS installers certificate.