I have been busy all afternoon sorting out my terrain issues. There are no pictures but it has been a case of levelling and reinstalling lots all afternoon so there is nothing new to show.
I would like to thank very much indeed both @Rflong7 and @Karritz for their instructions and videos on levelling terrain or placing lots on uneven terrain. I might well have abandoned this project without that guidance to sort out the mess. I have learned now that it is far better to make sure terrain is totally flat before even attempting to build.