Catalina preventing me from restoring from time machine, advice?

So I backed up my computer 3 days ago on time machine, when I had High Sierra, and then proceeded to upgrade to Catalina. For whatever reason the system does not run well on my mac and i'd like to revert my computer back, however when trying to use time machine I get this message:

'The system cannot be restored onto

this disk because HFS systems can't be restored to space sharing APFS

volumes. Reinstall MacOS on this disk and then use Migration Assistant

to transfer data from your backup assistant.'

I was advised to try in internet recovery mode but when trying to select my computers drive I am forever stuck on 'searching for disks...' so this isn't an option either it seems.

So I'm thinking that, if I factory reset my computer, I can then use my time machine to bring it back to how it was pre Catalina. Does this sound right? I just want to double check before I wipe my computer if theres a possibility time machine won't work, I figure the message about the system being unable to be restored is because of Catalina, but a factory reset should get rid of Catalina right? Any help would be appreciated as I need my laptop working asap and its driving me a bit mad now, thanks!