I have a laptop with 7th gen i3 with only Ubuntu installed and it's working perfectly for me. I use it for school work, so mostly LibreOffice and a little bit of CAD and I haven't seen any issues. I've added an extra 4GB of ram and a 30€ M.2 SSD which the OS is installed on, but it only makes it slightly faster. Currently sitting at 3GB RAM usage with multiple tabs on firefox, steam, thunderbird and discord open. If you want programs to open fast etc. you really need an SSD and maybe a bit more RAM. 120GB drives should be pretty cheap by now and they work fine, especially if you have that 1TB HDD alongside with it.
My apologies, I don't have a solution for you. You might look for a busted laptop with compatible ram for cheap/free, at least relieve that problem, that's the best I can come up with.
