Dear fariz162, wail127, aymanbhrr and those (9) with this 'same problem',
Over the past 24 hours I've successfully updated two iPads (both 7th generation with 32GB Storage Capacity) to iOS 17.7 and then to iOS 18.0.1. It may be because the iPads have a small capacity that no data seems to have been lost, as has been wail127's unfortunate previous experience.
Updating to 17.7 first effectively doubled the amount of space needed to update to 18.0.1 (but not the [extra] space occupied by the update itself once loaded onto the iPads).
So if you are faced with both these updates together, I would recommend skipping 17.7 and updating straight to 18.0.1. This may enable you to update to 18.0.1 without connecting to another computer/using the iTunes workaround.
In my case, I had already updated to 17.7, doubling the space required to update to 18.0.1 from 6.2Gb to 12.4GB. No-one in this thread has explained why this 'doubling' happens.
I have a Windows PC, connected my iPad(s) to it via the Lightning-USB cable and used the iTunes 'workaround' to update my iPad(s) to 18.0.1 : Update software on iPhone, iPad, or iPod touch in iTunes on PC - Apple Support
To do this I first had to download i-Tunes onto my Windows laptop: Download iTunes for Windows - Apple Support
We use our iPads primarily for communication so do not require larger capacity except for iOS updates . I plan to use the iTunes workaround in future rather than making 'deletions' to free up space (usually of videos and photos e.g. by moving them to OneDrive and/or iCloud).
Thank you to all who contributed to this solution and to the 'Apple Support Community Staff' who moderated everyone's comments.
