General comment
It's a good thought. General comment on octopus, when I said they're looking for a standard install, this is what I'm talking about. They'll have 1 panel size available and order 1000s of them. Maybe you can go with another supplier and they'll measure the panels carefully and get the absolute maximum on them, but Octopus will probably be cheaper (because standard and bought in bulk) so the optimisation may not be cost effectiveOne thing I would advise is also to consider lower capacity panels. You may find that because they're smaller than the larger ones, you can actually get more of them up on your roof and have more capacity.
So make sure you know your roof capacity.