So we have progress!!
She came out today and ate some chicken next to me! Let me stroke her without too much hissing (there was some still though but once I get past the initial hiss she enjoys strokes around her ears!). She didn't like being picked up too much, I placed her on my lap and stroked her but as soon as she wanted to go I just let her run away.
Partner also had progress tonight, she was playing with her wand toy and ate her food next to him too (turns out she can't resist tuna).
Thanks all for your advice!
Is it going to be best to hold Nala whilst Simba comes and sniffs around or just let them two sniff each other?
I'm willing to be patient as she is so beautiful and I can't wait for her to come out of her shell, I'm more frustrated that the breeder didn't socialise these kittens (there was one kitten in the litter that had THE most beautiful rosettes but hissed and climbed up the doors when you got anywhere near her
). If I didn't have a full time job I'd want to take all the kittens and look after them