Appearance Incorrect

Hi, new to wordpress and the forum so excuse what is probably a very simple issue to fix!

I recently updated my existing website https://www.penuelscout.org.uk (a frontpage-designed site I wrote a few years ago) with a weaver-themed wordpress site so I could make it easier to post new content and multiple “admins”.

I uploaded and installed the wordpress file with no great difficulty and while I was migrating the content from the existing site to the wordpress I had them running side-by-side (so the wordpress site was at https://www.penuelscouts.org.uk/wordpress). This all worked very well and yesterday I finished copying across the content to the wordpress pages, did a last bit of tidying-up and was ready to go.

Then I backed-up my existing site files (using Filezilla) and deleted them from the server, and instated the wordpress files into the root directory.

Now, when I type https://www.penuelscouts.org.uk nothing comes up, but if I leave the www. off the page displays but as text only (and in every browser). I’m so sure this is a rookie error that I’ll kick myself when someone points out what I’ve done wrong, but for the life of me I can’t figure it out!

All suggestions very gratefully received!