OK so Iv'e just found out that I cant build my conservatory as I have a manhole right in the middle of the proposed conservatory.
I had a builder come round and he said it would be no problem to raise the manhole (only around 20cm)
I have called thames water to apply for permission and they have told my that as it is a public sewer we cant raise it.
Can that be right? It might not be possible to divert the sewer so what options does it leave?