Hey!
Many thanks to both of you for your feedback!
In the end, it was the Raspberry Pi Imager tool that got the job done - excellent!
Unfortunately, the weekly builds link didn't work for me, the same problem continued. I also, out of curiosity, tried Firefox (as was trying Safari and Chrome) and pressed the resume function every time the download failed along the way - that method completed the download.
Anyway, thanks again for your help re the Raspberry Pi Imager help! :)