When I test ths website on my iPhone the browser tells me that the page is "Not Secure". This is simply that my site does not have an SSL Certificate. It does not mean that anyone is a risk in viewing my site, it is more the fact that there is a recognition that there are malicious websites out there on the Internet and way of "certifying" that you are what you appear to be (the URL shown in your browser - will be https:// for a site with SSL).
If you implementing a simple solution similar to one that I a going to use for my Parish Council site I am of the opinion that you do not need an SSL Certificate. Should parishoners express concern that the site shows as "Not Secure" my Hosting service can provide one for £15 per annum.
SSL - Secure Sockets Layer
You can search the Internet to find more information on SSL and TLS.
The understanding of what SSL/TLS means to your Internet activity is, I believe, confused. SSL/TLS in itself does not fully protect you when you are online. It helps to ensure that the communications between you and the service you are using are encrypted, this is useful if your are exchanging sensitive information such as your credit card number and a bank account statement from your bank. It also ensures that you are dealing with who you think use are as the site you are accessing has to have a certificate. This certificate is issued to the webite owner and your browser will check that it is valid.
Simple websites, such as a Parish Council site, that do not require visitors to "join", log-on or post information to them - do not require this level of security. Although some browsers will tell you that the site is "Not Secure" this is only because an SSL cerificate cannot to checked. If is this is important to you and/or visitors then you can cheaply purchase and install a certificate.