Wow. "Superstructure" ! That was not an easy piece of the jigsaw.
I am not sure how much it will help you though.
It might be easier if you know which questions might help to lead you in.
I have made a start. The questions I can do are 17a, 17d, 18 and 20 which was my first one in. From these I managed the long one along the bottom.
Apart from that there are 11 and 6 which work together nicely.