How slow is your 4g? My home WiFi is 4g and it runs no bother. A 5gb file downloads in around 40mins (an hour tops) - and I live in the back of beyond, hence the need for 4g.
That's faster than mine! But then I do use it a lot, Three may be limiting my speed, but as long as I can stream movies / youtube that's all I use it for really. Didn't want to get into a long term broadband contract since my job at the University is only temporary.
@RichW9 - 'storedownloadd' is the the App Store daemon (good). 'sending status', not entirely sure to be honest as I can't say I've seen that log message before, although typically you'll see errors if anything is amiss and i'd take a hunch that it's downloading albeit extremely slowly - slow connection or your network is throttling Apple's update servers.
Leave it an hour and see what it says.
Otherwise, try and use an alternative connection or if you know anyone with a Mac (and internet access and a 8GB+ USB drive), then you can create a bootable USB drive of the Sierra installer (which arguably is the easy option).
I think you're right it seems to be moving slowly forward. Will leave it overnight then check it out in the morning, hopefully will work if not will try USB boot drive thanks. Never had an iMac before, not really something I'm interested in as my PC does everything I need here, but will try it out anyway.
Thanks again for the help.