It maybe worth backing the Windows 7 system up completely with a free program like Macrium reflect. This will give you the option to restore the system back "as is."
Once your completely backed up, using the Windows 10 media creation tool from Microsoft’s website will allow you to create and install Windows 10 from a USB flash drive. I find it best to create a folder on the system drive that Windows 7 is installed on. Call the folder W10 for example. Copy the files from the USB flash drive to the W10 folder and run the setup.exe from the W10 folder. In my experience, this provides the least hassle-free way to upgrade from Win 7 to Win10.
Depending on what hardware you have and version of Windows you have purchased, you may find you can upgrade at no cost, yes, even now. Depending on what antivirus/security solution your using, you may want to uninstall it before the upgrade. I have never had a problem with leaving Webroot or Bitdefender in place however; your mileage may vary.
Ultimately this would give you time to test things out and make a checklist of items that may require attention. Try to plan the test at a time where you can live without the system for a weekend or more. Make sure you have the time to test out the things that are important to you. If your not happy you can roll back using the Macrium reflect backup you made.
Depending on how much data you have, the time to backup completely and restore completely may take many hours, in some cases days. If you can operate from the other computer you mentioned, for critical tasks, over that time you should be in an okay place. Take the time to consider what critical tasks you would need to perform on the other computer and confirm it will be able to handle those tasks.
If you're not comfortable with trying the processes above you can research the backup and restore processes at Macrium's website. They have excellent documentation. Ultimately you may wish to rely on a technically proficient friend to assist. If you’re thinking of contacting a professional, try to agree on a fixed price as this could become expensive.
Security update support ends for Windows 7 on the 14th of Jan 2020 save for very special cases. It would be prudent to ensure your on Windows 10 before this date. You have plenty of time between now and then to plan and test. Whatever you decide, make sure your completely backed up and you have confidence with your ability or that of software you choose to restore from that backup.
Clean installs are almost always better than inplace upgrades but that said Windows 10 handles in place upgrades far better than any previous version of Windows.