New Build conservatory advice needed

[HJSolutions]

Hi Guys,
First time posting in this forum and would like to try and get some advice if possible, here is my situation.
I am planning on building a conservatory on the back of my house, measurement's are 16' wide x 8' depth, the connie is a full height design with raised bottom pcv panels, so no dwarf wall as such. It will be built onto the kitchen but I intend on leaving the external grade door on and is does not fill any more than 50% of the properties land, so thinking that Planning permission and building regs are not necc. I have a couple of issues/concerns that hopefully one of you guys might be able to help me with.
Firstly, the intended base is currently a patio that I laid, under this patio is a 150mm concrete base put down when the house was built, being that I am not subject to building regs is it acceptable to lay rows of concrete blocks built up to the existing DPC of this house and fit the connie frame to the blocks?. This would give the the overall height of base approx 300mm including blocks and existing base.
The next problem I have is that my house is a semi detached and under the connie is a sewer and manhole that serves my house and the next 2 houses to my right. I have contacted Deleted and suffolk water in an attempt to acsertain as to if the sewer is public or private. Obviously if is public I will then apply for the build over agreement. I intend on leaving the manhole in place and fit a double sealed cover, the internal floor of the connie will be mounted on wood beams and then leaving an access panel for access to the manhole. I also have soil stack and hopper for bath waste that I intend on piping the waste through a boss into the stack and boxing or putting a gulley over the existing drain and leave the waste going to it with another access panel in the floor. My concern is that if the sewer comes back as being private and I do do what I have proposed is it possible for the weight of the connie to at some point collapse the sewer?

Any help or advice would be greatly appreciated.
Best Regards,
James

[HJSolutions]

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