After that, they each wrote an additional Red Dwarf novel individually / separately. Personally I've never come across those last two novels, although I always check for them whenever visiting a used book store. Maybe they were only released in the UK. They're available on Amazon in the US, but I haven't quite given up hope on stumbling across them naturally yet...
Backwards spent the first section of the book in the backwards universe, over years. It’s has an interesting exploration of the implications of that universe. By comparison Last Human wraps that up in a few pages and spends most of its time dealing with android assassins.