So... I found this regarding reading the required information via FEL mode. However, running these commands:
./sunxi-fel read 0x42400000 0x82d0 boot1.header
./sunxi-fel read 0x43000000 0x20000 script.bin
fail with usb_bulk_send() ERROR -7: Operation timed out which I believe may be related to size limits as outline here.
I don't know what length would be appropriate to avoid the error. If I knew how addresses work (I read something about 8 bits but didn't quite grasp it) I could script a read in chunks and concatenate them into a single binary. Apologies, I know I need to learn on my own but if someone could just point me in the right direction I'll figure it out myself. Many thanks
EDIT: Ignore the above, boot1 isn't loaded so cannot be read. My bad!