Okay, so she (and you!) have had an incredibly challenging start in life and she has missed virtually all of the schooling her peers have had, as well of course as missing on all the pre-school experiences, from Nursery and playgroups to just playing at home. SPending that long in hospital must have been draining for you all 
If I have read it right though, she is now (relatively) well, but at home because she is shielding ?
She seems not to have any difficulties with her cognition, but obviously hasn't had the chance to start with all her peers, so you, as her Mum would like to help her, so that when she is able to go back to school, she is on her way to begin to catch up with where her peers are ?
In which case, I think I would explain to her that it is a school day, and that you and she will be 'doing school' at home. I'd structure it to some extent. But short sessions. Start off by picking up Joe Wicks PE on You Tube from the last lockdown. Then have your 'timetable' - some of which will be just 10 min slots - yes, include
- some pre-reading skills,
- include something to do with number,
- include something to do with more 'practical maths' (cooking, playing in water, sorting, ordering, using language to do with size and comparison),
- do something to do with pre-reading skills - both fine motor fun and also "structuring language" (ie, she makes up a story and you write it down)
- do music
- do art
- do things like simple jigsaws
If you want ideas for fun things to do, ask away, there are lots of folks on here who will happily help you. 