Thanks everyone for your advice here, interesting background there too Simon, thank you.
Had a great chat with OZ 4/4 today too, feeling much more relaxed about it and have a plan of action - involves replacing the springs of course.
Many thanks for your time and advice OZ, really appreciated that ππ»πΎπ
I missed the fact that you have decided to change the springs when I made my previous reply. I would caution against using 4 seater springs unless you really enjoy a hard ride

We use our car a lot for touring, about 12,000km a year, and we found the 5 leaf 2 seater springs gave a very hard and uncomfortable ride. I don't know for sure but I imagine that the 4 leaf 4 seater springs would be very hard for a 4/4 2 seater.