@s18000rpm, the site I had mentioned earlier already gives the option for languages, but it does not specifically give an option for Single Language; that was the problem I was encountering. But as
@whitestar_999 has said, Microsoft has stopped giving a separate Single Language ISO. So you have to download the 4.4 GB ISO of x64 from the MS site, which contains both Home and Pro, and also Single Language, and during installation, it will automatically install the version that is allowed on that particular computer, in my case, the Single Language one.
Strange thing is, when I go to the windowsiso.net site, it doesn't give any option to open the Single Language ISO download page for version 1709; it mentions it, but it is not a clickable link to open another page. I could have sworn that I had opened that page earlier and seen the download for the Single Language ISOs. Maybe it was the 1607 Anniversary update page I had opened...
A few months back, I had made a system backup image using EaseUS ToDo Backup. What I'm planning to do now is, first I'll download the x64 1709 ISO from the MS site, then revert back to the 1607 image which has only drivers installed and no other clutter, then extract and run the 1709 setup, and after completion of the setup, make another system image to replace the 1607 image. This way, I'll have both the ISO, and a working system image backup of the latest version.

If I do a clean install of 1709 now, I'll have to install the drivers again.