Cant Add Blog to site

I have inherited a site from someone, who removed the blog feature. I have been asked to add the blog feature back in, but when I create a static page and assign it as the post page, the previeiw shows the homepage, and if I navigate directly to it, it shows the posts but displays the a template layout that does not exist as far as I can tell.

the site is https://www.aupair.berlitzmanchester.com

and the direct link is https://www.aupair.berlitzmanchester.com/news

any help world be appreciated

thanks