I am impressed by all the resourcefulness, creativity and diversity of your solution oriented responses. Brilliant.
Andrea - I don't think you mentioned which operating system you are running. If you are running Windows 10, MS disabled the option to turn off, or control the installation of updates. And we don't know your level of expertise around installation of operating systems. If you are reformatting and doing a clean install, you need drivers and all kinds of little bits of software to create a new harmonious union of software, firmware and hardware. Can be tricky. If your one computer is part way through a clean install and you need tech support or to look something up on the internet, and you don't have access to the internet, that's a tough place to be.
And you boldly own your cheap(?), stingy(?) frugal(?) mental posture, which is so curious. I get the impression, please correct me if I am wrong, that you are not impoverished, you have the money and could pay for X, just don't want to, which is something I'd be interested in exploring, don't know if you feel the same way. Are you as generous with others as you hope others will be with you? Do we have a forum on the mindset behind cheap(?), stingy(?) frugal(?).
Does everybody know about Freecycle.org? Great online resource to post your "offers" and "wants" out into your local community. You can request a working laptop or desktop. Post things you no longer need or want and give them a second life.
Another option is your local computer geek club. Your library can help you find them, or a community center. Might be a good place to get technical support if you need help installing an OS, finding someone who might be willing to do an install of their software on your computer without giving you their only disk.
Look for a PC or a Linux Meetup. Try Meetup.com
Go to your local college or university, they can point you in the direction of a computer club, and/or an IT department. Or a computer student who could get credit for putting his newly acquired skills into practice.
Are you a senior or on disability? Some communities give away reconditioned/refurbished/used computers to those in need.
This is link for free antivirus software, which would be useful if you are not getting updates. (i am not affiliated in any way with any of these. Please check them out for yourself.)
Here is a search for Linux software:
And here is a search to find sites to download software for free;