As I understand it, the UK is sort of unusual in that they don't generally have vehicles prebought by a dealer ready for sale, so all i3 vehicles are essentially ordered. That somewhat depends on allocations and how things are going now.
Given the world-wide issues with the virus, I think things are sort of up in the air...if they close the factory, or some of the suppliers slow down their deliveries, whatever was normal, may be different for maybe many months. If it gets delayed too long, you might run into the end of the model year and may end up with a 2021 if you still want it.
It's a new situation, and you may not get an accurate idea...maybe of what was, but things are different now.