Why not just use Cloudflare? They do SSL termination for free, plus you'd get caching to boot.
So long as your site doens't have SSL you shouldn't be linking people to it. You're under no obligation to drop everything and fix your web server security but you should really stop using it until you do.
So far I've had a less than stellar experience with letsencrypt, so I'm not quite ready to go all free-certs just quite yet. It also requires a rebuild of my web-server[1] which I've been putting off for a very long time already.
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[1] See my other post in this thread.