(Bear with me, almost up to the point where I’m current and actually lost).
I’ve noticed that only some of the emulators are present as I page left and right, and no sign of mame or the ZX Spectrum, so something is obviously wrong as other emulators are present. Back to google search and eventually I find out that the emulators do not appear in the list until you actually put a rom in there, OK thats a problem explained.
So I find some instructions on how to load roms from a USB stick and it seems pretty straight forward. I format a USB stick FAT32 and add a ‘retropie’ folder, fire up the Pi and put the stick in. Wait a couple minutes, take it out and put it into the PC. And now the retropie folder has subfolders for all the roms, it really is very easy from here on in (I think at this point). So lets go for the obvious, the old original space invaders. Found the rom (they are so small!) and downloaded, it’s a zip file. Easy this time as windows10 can unzip right there, so I do that and end up with around 5 files. I copy these to the Mame4all rom subfolder, no idea how it knows the name or anything but if it’s magic thats fine by me. I put the USB stick back into the Pi, nothing seems to have happened. Instructions say to reboot, I have no idea how to reboot so I unplug the power and back on. Again through the emulators, still no sign of mame, hmmm. Back to google.